Maharashtra Board Class 8 Science Chapter 7 Metals and Nonmetals Solutions

Std 8 Science Chapter 7 Metals And Nonmetals Question Answer Maharashtra Board

1. Complete The Table:

Question a.

Property of metal	Use in everyday life
i. Ductility
ii. Malleability
iii. Conduction of heat
iv. Conduction of electricity
v. Sonority

Answer:

Property of metal	Use in everyday life
i. Ductility	i. Gold, silver ornaments
ii. Malleability	ii. Aluminium sheets, galvanised sheets
iii. Conduction of heat	iii. Stainless steel vessels, copper vessels, boilers
iv. Conduction of electricity	iv. Copper wires
v. Sonority	v. Brass articles

In simple words: This table categorizes different properties of metals like ductility, malleability, heat and electricity conduction, and sonority, linking each property to its common application in daily life.

🎯 Exam Tip: Understanding the practical applications of metallic properties helps in recalling and explaining them accurately in exams.

 

2. Identify The Odd Term.

Question a. Gold, Silver, Iron, Diamond.

Answer: Diamond. (Others are metals.)In simple words: Diamond is the odd one out because it is a non-metal, while gold, silver, and iron are all metals.

🎯 Exam Tip: For "odd one out" questions, always provide the reason for your selection, clearly stating what makes the chosen term different from the rest.

 

Question b. Ductility, Brittleness, Sonority, Malleability.

Answer: Brittleness. (Other properties are metallic properties.)In simple words: Brittleness is a property associated with non-metals, whereas ductility, sonority, and malleability are characteristic properties of metals.

🎯 Exam Tip: Knowing the distinct physical properties of metals and non-metals is crucial for identification and classification questions.

 

Question c. Carbon, Bromine, Sulphur, Phosphorus.

Answer: Bromine. (Others are solids.)In simple words: Bromine is the only non-metal in the list that exists as a liquid at room temperature, while carbon, sulphur, and phosphorus are solids.

🎯 Exam Tip: Remember common exceptions to general rules, such as bromine being a liquid non-metal and mercury being a liquid metal, as these are frequently tested.

 

Question d. Brass, Bronze, Iron, Steel.

Answer: Iron. (Others are alloys.)In simple words: Iron is a pure metal, whereas brass, bronze, and steel are all alloys, which are mixtures of metals or metals with non-metals.

🎯 Exam Tip: Differentiate between pure metals and alloys, as their compositions and properties can vary significantly.

 

3. Give Scientific Reasons:

Question a. The stainless steel vessels in kitchen have copper coating on the bottom.

Answer:1. Stainless steel is an alloy of iron - with carbon, chromium and nickel. 2. The conductivity of copper is higher than that of iron in steel. Copper heats uniformly and faster. The time for cooking is reduced, as a result it saves fuel. Hence, the stainless steel vessels in kitchen have copper coating on the bottom.In simple words: Copper is a better conductor of heat than stainless steel. Coating the bottom of stainless steel vessels with copper ensures more even and faster heating, thus saving cooking time and fuel.

🎯 Exam Tip: When giving scientific reasons, ensure your explanation clearly links the observed phenomenon to the scientific principle, providing cause and effect.

 

Question b. Copper and brass vessels are cleaned with lemon.

Answer:1. Copper undergoes oxidation in air to form black copper oxide. Copper oxide reacts slowly with carbon dioxide in air and gains a green coat. This green substance is copper carbonate. 2. Lemon contains acid. The acid dissolves the green coating of basic copper carbonate present on the surface of a tarnished copper and brass vessels and makes them shiny again.In simple words: Copper and brass tarnish over time, forming a green layer of basic copper carbonate. Lemon contains citric acid, which reacts with and dissolves this green layer, restoring the shine of the vessels.

🎯 Exam Tip: Chemical reactions in everyday life, especially those involving acids and bases, are important. Explain the specific compounds involved in the tarnishing and cleaning process.

 

Question c. Sodium metal is kept in kerosene.

Answer:1. Sodium reacts so vigorously with atmospheric oxygen and water that it catches fire if kept in the open. 2. It does not react with kerosene and sinks in it. Hence, to protect sodium and to prevent accidental fires it is always kept in kerosene.In simple words: Sodium is a highly reactive metal that reacts violently with air and water. Kerosene is an unreactive liquid that protects sodium from exposure to oxygen and moisture, preventing fires.

🎯 Exam Tip: Highlight the extreme reactivity of certain alkali metals like sodium and potassium, and the specific precautions taken for their storage.

 

4. Answer The Following:

Question a. What is done to prevent corrosion of metals?

Answer: By applying a layer of paint, oil, grease or varnish on the surface of a metal to prevent corrosion. Also plating with noncorroding metal is done. Iron is coated with thin layer of zinc. Due to these processes the contact of metal surface with air is lost and corrosion is prevented.In simple words: Corrosion is prevented by applying protective layers like paint, oil, or varnish, or by coating metals with non-corroding metals like zinc (galvanization), which stops contact with air and moisture.

🎯 Exam Tip: List various methods of corrosion prevention and briefly explain the principle behind each, such as creating a barrier or using a sacrificial metal.

 

Question b. What are the metals that make the alloys brass and bronze?

Answer: The alloy brass is formed from copper and zinc and the alloy bronze is formed from copper and tin.In simple words: Brass is an alloy made from copper and zinc, while bronze is an alloy made from copper and tin.

🎯 Exam Tip: Memorize the common constituent metals for important alloys like brass, bronze, and stainless steel.

 

Question c. What are the adverse effects of i corrosion?

Answer:1. A reddish coloured deposit (rust) is formed on iron by reaction with oxygen gas. 2. A greenish coloured deposit (copper carbonate) is formed on copper by reaction with carbon dioxide. 3. A blackish coloured deposit is formed (silver sulphide) on silver. 4. Corrosion causes damages to car bodies, bridges, iron railings, ships specially those of iron, silver articles and copper vessels.In simple words: Corrosion leads to the formation of undesirable layers (like rust on iron, green carbonate on copper, black sulphide on silver) and causes significant damage to structures, vehicles, and household items, reducing their lifespan and strength.

🎯 Exam Tip: Describe the specific types of corrosion (e.g., rusting) and their visible effects, along with the practical implications and damages caused.

 

Question 5. Three experiments to study the process of rusting are given below. Observe the three test tubes and answer the following questions.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र तीन टेस्ट ट्यूबों में लोहे के जंग लगने की प्रक्रिया को दर्शाता है। टेस्ट ट्यूब 1 में पानी और हवा दोनों हैं जिससे लोहे पर जंग लगती है। टेस्ट ट्यूब 2 में उबला हुआ पानी (जिसमें हवा नहीं है) और ऊपर तेल की परत है जो हवा को रोकती है, जिससे जंग नहीं लगती। टेस्ट ट्यूब 3 में निर्जल कैल्शियम क्लोराइड है जो हवा से नमी को सोख लेता है, इसलिए यहाँ भी जंग नहीं लगती।In simple words: The diagram shows three test tubes experimenting with rusting: one with air and water for rusting, one with boiled water and oil to prevent air contact, and one with calcium chloride to absorb moisture, preventing rusting.

🎯 Exam Tip: When analyzing experimental setups, clearly identify the control variables and the conditions that are being tested, and relate them directly to the outcome observed.

 

Question a. Why the nail in the test tube 2 is not rusted?

Answer: In the test tube 2, oil cuts the supply of air to nail due to which oxidation of nail is prevented and boiled water is free from gases. Hence, the nail in the test tube 2 is not rusted.In simple words: The nail in test tube 2 doesn't rust because the oil layer prevents air (oxygen) from reaching the nail, and the boiled water lacks dissolved oxygen, both essential for rusting.

🎯 Exam Tip: Emphasize that both oxygen (from air) and water are necessary conditions for rusting to occur; removing either prevents the process.

 

Question b. Why is the nail in the test tube 1 is rusted highly?

Answer: The nail in the test tube 1 is highly rusted because nail is in contact with water and air. The oxidation process is fast.In simple words: Test tube 1 provides both water and air (oxygen) in direct contact with the nail, creating ideal conditions for rapid oxidation and thus, extensive rusting.

🎯 Exam Tip: Explain that the presence of both oxygen and water accelerates the electrochemical process of rusting, leading to significant corrosion.

 

Question c. Would the nail in the test tube 3 get rusted?

Answer: No change is observed in the test tube 3. Nail remains as it is because the calcium chloride absorbs moisture, making the air dry, thus preventing rusting of the nail.In simple words: No, the nail in test tube 3 will not rust because the calcium chloride absorbs all the moisture from the air, ensuring a dry environment where rusting cannot occur.

🎯 Exam Tip: Highlight the role of moisture in rusting; without it, even in the presence of air, iron will not corrode.

 

Project:

Question a. How is the Varkha or silver foil used in sweets made? Collect the information about which metals are used to make 'Varkha'.

Answer:In simple words: Varkha, the edible silver foil on sweets, is traditionally made by hammering pure silver into extremely thin sheets. While silver is the primary metal, sometimes aluminum is used as a cheaper alternative, though silver is preferred for its safety and traditional value.

🎯 Exam Tip: Research-based questions require accurate factual information. Ensure to mention the primary metal (silver) and any common substitutes (aluminum) when discussing Varkha.

 

Class 8 Science Chapter 7 Metals And Nonmetals Additional Important Questions And Answers

Rewrite The Sentences After Filling The Blanks:

Question 1. Gold of 100% purity is ............ carat gold.

Answer: Gold of 100% purity is 24 carat gold.In simple words: Gold that is completely pure, without any other metals mixed in, is known as 24-carat gold.

🎯 Exam Tip: Remember that 24-carat represents 100% purity in gold; lower carat values indicate an alloy.

 

Question 2. The stainless steel utensils used at home are made of an alloy of iron with carbon, ............ and ............

Answer: The stainless steel utensils used at home are made of an alloy of iron with carbon, nickel and chromium.In simple words: Stainless steel is an alloy primarily composed of iron, carbon, nickel, and chromium, which gives it its rust-resistant properties.

🎯 Exam Tip: Knowing the composition of common alloys like stainless steel is important for understanding their properties and uses.

 

Question 3. ............ is used in medicines.

Answer: Silver is used in medicines.In simple words: Silver has antibacterial properties, making it useful in certain medical applications and medicines.

🎯 Exam Tip: Be aware of the less common but important applications of metals beyond their typical industrial uses, such as silver's medicinal properties.

 

Question 4. To prepare ornaments ............ carat gold is used.

Answer: To prepare ornaments 22 carat gold is used.In simple words: For making ornaments, 22-carat gold is typically used because pure 24-carat gold is too soft and easily deforms.

🎯 Exam Tip: Differentiate between the purity of gold (24-carat) and the practical purity used for jewelry (typically 22-carat) due to malleability concerns.

 

Question 5. Non-metals are ............ conductors of heat and electricity.

Answer: Non-metals are bad conductors of heat and electricity.In simple words: Generally, non-metals are poor conductors, meaning they do not easily allow heat or electricity to pass through them.

🎯 Exam Tip: Remember the general rule that non-metals are poor conductors, with graphite being a notable exception for electrical conductivity.

 

Question 6. Non-metals form ............ oxides.

Answer: Non-metals form acidic oxides.In simple words: When non-metals react with oxygen, they typically form oxides that are acidic in nature, unlike metal oxides which are usually basic.

🎯 Exam Tip: Distinguish between the acidic nature of non-metal oxides and the basic nature of metal oxides, as this is a fundamental chemical property.

 

Question 7. Some element can be hammered into thin sheets. This property is called ............

Answer: Some element can be hammered into thin sheets. This property is called malleability.In simple words: The ability of a substance, usually a metal, to be flattened into thin sheets by hammering without breaking is called malleability.

🎯 Exam Tip: Clearly define and differentiate between key physical properties of metals like malleability (sheets) and ductility (wires).

 

Question 8. Iodine and ............ are the two non-metals having typical metallic lustre.

Answer: Iodine and diamond are the two non-metals having typical metallic lustre.In simple words: While most non-metals are dull, iodine and diamond are exceptions as they exhibit a shiny, metallic-like appearance.

🎯 Exam Tip: Note exceptions to general properties, such as non-metals like iodine and diamond having lustre, as these often appear in questions.

 

Question 9. Non-metals form ............ ions by gain of electrons.

Answer: Non-metals form negative ions by gain of electrons.In simple words: Non-metals tend to gain electrons to achieve a stable electron configuration, thereby forming negatively charged ions, also known as anions.

🎯 Exam Tip: Understand the fundamental difference in ion formation between metals (lose electrons, form positive ions) and non-metals (gain electrons, form negative ions).

 

Question 10. During formation of positively charged ion, atom of metal ............

Answer: During formation of positively charged ion, atom of metal lose electrons.In simple words: When a metal atom transforms into a positively charged ion, it does so by losing one or more electrons from its outermost shell.

🎯 Exam Tip: Connect the formation of positive ions (cations) with the loss of electrons, which is a characteristic behavior of metals.

 

Rewrite The Following Statements By Selecting The Correct Options:

Question 1. Metalloids have properties of ............
(a) metals
(b) non-metals
(c) both metals and non-metals
(d) neither metals nor non-metals

Answer: (c) both metals and non-metalsIn simple words: Metalloids are elements that exhibit characteristics intermediate between those of metals and non-metals.

🎯 Exam Tip: The definition of a metalloid is key here; it bridges the gap between typical metallic and non-metallic properties.

 

Question 2. ............ is a metal.
(a) Hg
(b) S
(c) P
(d) Br

Answer: (a) HgIn simple words: Hg stands for Mercury, which is a metal, while S (Sulphur), P (Phosphorus), and Br (Bromine) are non-metals.

🎯 Exam Tip: Recognize common chemical symbols for elements and know their classification as metals, non-metals, or metalloids.

 

Question 3. ............ is a non-metal.
(a) Aug
(b) Ag
(c) Br
(d) Cu

Answer: (c) BrIn simple words: Br represents Bromine, which is a non-metal, whereas Aug (Gold), Ag (Silver), and Cu (Copper) are metals.

🎯 Exam Tip: Familiarity with symbols of common elements helps in quickly identifying metals and non-metals in multiple-choice questions.

 

Question 4. ............ is a metalloid.
(a) Aluminium
(b) Antimony
(c) Zinc
(d) Mercury

Answer: (b) AntimonyIn simple words: Antimony is classified as a metalloid due to its properties falling between those of metals and non-metals.

🎯 Exam Tip: Learn examples of metalloids, such as silicon, germanium, arsenic, antimony, and tellurium.

 

Question 5. ............ is a metal which is in liquid form at ordinary temperature.
(a) Gallium
(b) Magnesium
(c) Sodium
(d) Scandium

Answer: (a) GalliumIn simple words: Gallium is a unique metal that melts at a very low temperature, making it liquid at or just above room temperature.

🎯 Exam Tip: While mercury is the most well-known liquid metal at room temperature, remember other metals like gallium that also exhibit this property at ordinary temperatures.

 

Question 6. ............ is an acidic oxide.
(a) Na\(_{2}\)O
(b) CO\(_{2}\)
(c) FeOs
(d) H\(_{2}\)O

Answer: (b) CO\(_{2}\)In simple words: Carbon dioxide (CO\(_{2}\)) is formed from a non-metal (carbon) and typically forms acidic solutions when dissolved in water, making it an acidic oxide.

🎯 Exam Tip: Recall that oxides of non-metals are generally acidic, while oxides of metals are typically basic.

 

Question 7. The valence electron in ............ atom is 1.
(a) magnesium
(b) sodium
(c) silicon
(d) aluminium

Answer: (b) sodiumIn simple words: Sodium (Na) belongs to Group 1 of the periodic table, meaning it has one valence electron in its outermost shell.

🎯 Exam Tip: The number of valence electrons often corresponds to the group number for main group elements and dictates their chemical reactivity.

 

Question 8. The electronic configuration of oxygen is ............
(a) 2, 5
(b) 2, 6
(c) 2, 4
(d) 2, 8, 6

Answer: (b) 2, 6In simple words: Oxygen has an atomic number of 8, meaning it has 8 electrons arranged with 2 in the first shell and 6 in the outermost shell.

🎯 Exam Tip: Practice writing electronic configurations for the first 20 elements, as this helps understand reactivity and bonding.

 

Question 9. Pure ............ is soft.
(a) aluminium
(b) silver
(c) gold
(d) platinum

Answer: (c) goldIn simple words: Pure gold (24-carat) is inherently soft and can be easily bent or damaged, which is why it's usually alloyed for jewelry.

🎯 Exam Tip: Remember that the softness of pure gold necessitates alloying with other metals like copper or silver for practical applications like jewelry making.

 

Question 10. ............ is a highly malleable metal.
(a) Iron
(b) Nickel
(c) Manganese
(d) Aluminium

Answer: (d) AluminiumIn simple words: Aluminium is known for its excellent malleability, allowing it to be easily hammered or rolled into thin sheets without breaking.

🎯 Exam Tip: Identify metals with pronounced malleability, such as gold, silver, and aluminium, which are often used in applications requiring thin sheets or foils.

 

Question 11. 22 carat gold is gold of ............ purity.
(a) 100%
(b) 91.66%
(c) 75%
(d) 44%

Answer: (b) 91.66%In simple words: 22-carat gold contains 22 parts of pure gold out of 24 total parts, which translates to approximately 91.66% purity.

🎯 Exam Tip: Understand the calculation of gold purity in carats: (Carat value / 24) * 100%.

 

State Whether The Following Statements Are True Or False:

Question 1. Metals are sonorous.

Answer: True.In simple words: Metals are sonorous, meaning they produce a ringing sound when struck, a property often used in bells.

🎯 Exam Tip: Recall that sonority is a characteristic physical property of metals, distinguishing them from most non-metals.

 

Question 2. Diamond is the softest natural substance.

Answer: False. (Diamond is the hardest natural substance.)In simple words: Diamond is actually the hardest known natural substance, not the softest.

🎯 Exam Tip: Correctly identify extreme properties like hardness; diamond's exceptional hardness is a key fact.

 

Question 3. The density of lithium is lower than water.

Answer: True.In simple words: Lithium is a very light metal with a density less than that of water, causing it to float.

🎯 Exam Tip: Note the low density of alkali metals like lithium, sodium, and potassium, which is an important physical property.

 

Question 4. Sulphur is brown in colour.

Answer: False. (Sulphur is yellow in colour.)In simple words: Sulphur is typically yellow in color, not brown.

🎯 Exam Tip: Remember the characteristic colors of common elements; sulphur's yellow color is a key identifier.

 

Question 5. Germanium is a metalloid.

Answer: True.In simple words: Germanium is an element that exhibits properties of both metals and non-metals, classifying it as a metalloid.

🎯 Exam Tip: Be able to identify common metalloids, including germanium, silicon, and arsenic.

 

Question 6. Ornaments are made from 24 carat gold.

Answer: False. (Ornaments are made from 22 carat gold.)In simple words: Ornaments are usually made from 22-carat gold, as 24-carat gold is too soft for intricate designs and durability.

🎯 Exam Tip: Reiterate the practical reason why pure 24-carat gold is not used for jewelry-making.

 

Question 7. A reddish coloured deposit is formed on iron by reaction with oxygen.

Answer: True.In simple words: When iron reacts with oxygen and moisture, it forms a reddish-brown flaky substance known as rust.

🎯 Exam Tip: The formation of rust (iron oxide) is a classic example of corrosion, important to understand.

 

Question 8. Palladium and rhodium are noble metals.

Answer: True.In simple words: Palladium and rhodium are indeed noble metals, known for their high resistance to corrosion and oxidation.

🎯 Exam Tip: Identify members of the noble metal group, which are unreactive metals like gold, platinum, palladium, and rhodium.

 

Question 9. The metal oxides are acidic in nature.

Answer: False. (The metal oxides are basic in nature.)In simple words: Metal oxides typically react with water to form bases, making them basic in nature, unlike non-metal oxides which are acidic.

🎯 Exam Tip: Differentiate between the chemical nature of metal oxides (basic) and non-metal oxides (acidic).

 

Question 10. The metal reacts with dilute acids to form a metal salt.

Answer: True.In simple words: Most reactive metals react with dilute acids to displace hydrogen and form a corresponding metal salt.

🎯 Exam Tip: This is a characteristic chemical property of many metals; remember the general reaction: Metal + Acid → Salt + Hydrogen gas.

 

Identify The Odd Term:

Question 1. Magnesium, Mercury, Sodium, Iron.

Answer: Mercury. (Others metals are in solid state at normal temperature.)In simple words: Mercury is the only liquid metal in the list at normal room temperature, while magnesium, sodium, and iron are solids.

🎯 Exam Tip: Always state the distinguishing characteristic that makes one term "odd" compared to the others.

 

Question 2. Magnesium, Aluminium, Sulphur, Copper.

Answer: Sulphur. (Others are metals.)In simple words: Sulphur is a non-metal, whereas magnesium, aluminium, and copper are all metals.

🎯 Exam Tip: Classifying elements as metals or non-metals is a fundamental step in identifying the odd one out in such questions.

 

Question 3. Iron, Copper, Graphite, Phosphorus.

Answer: Phosphorus. (Others are good conductors of electricity.)In simple words: Phosphorus is a non-metal and a poor conductor of electricity, while iron, copper, and graphite (an allotrope of carbon) are all good conductors.

🎯 Exam Tip: Remember graphite as an exception among non-metals for electrical conductivity, which can sometimes be a trick in these questions.

 

Question 4. Tin, Bronze, Steel, Stainless steel.

Answer: Tin. (Others are alloys.)In simple words: Tin is a pure metal, whereas bronze, steel, and stainless steel are all alloys, which are mixtures of metals.

🎯 Exam Tip: Distinguish between pure elements and alloys based on their definition and composition.

 

Consider The Relation Between The Items In The First Pair And Write The Correlation For Second Pair:

Question 1. Mercury : Metal : : Carbon : ............

Answer: Non-metalIn simple words: Mercury is a metal, so following the same pattern, carbon is a non-metal.

🎯 Exam Tip: For correlation questions, identify the relationship in the first pair (e.g., classification, property, use) and apply it to the second pair.

 

Question 2. Wood: Bad conductor of electricity : : Copper : ............

Answer: Good conductor or electricityIn simple words: Wood is a poor conductor of electricity, so conversely, copper is an excellent conductor of electricity.

🎯 Exam Tip: Ensure the correlation is logical and consistent. If the first pair shows a contrast, the second should too, or if it's a similarity, then the second should follow suit.

 

Question 3. Gold: Noble metal : : Copper: ............

Answer: MetalIn simple words: Gold is specifically a noble metal, while copper is a common reactive metal.

🎯 Exam Tip: Recognize sub-classifications of metals, such as noble metals, and apply the general classification (metal) where a specific one isn't applicable.

 

Question 4. Iron and carbon : Steel : : Copper and Tin : ............

Answer: BronzeIn simple words: Steel is an alloy made from iron and carbon, and similarly, bronze is an alloy made from copper and tin.

🎯 Exam Tip: This question tests knowledge of common alloy compositions; ensure you know which elements combine to form key alloys.

 

Question 5. 0:2, 6:: Mg: ............

Answer: 2, 8, 2.In simple words: The first pair shows the electronic configuration of Oxygen (O), so the second pair should be the electronic configuration of Magnesium (Mg). Oxygen (atomic number 8) has 2 electrons in the first shell and 6 in the second. Magnesium (atomic number 12) has 2 electrons in the first shell, 8 in the second, and 2 in the third.

🎯 Exam Tip: Correlation questions involving electronic configurations require recalling atomic numbers and the rules for filling electron shells.

 

Match The Columns:

Question 1.

Column 'A'	Column 'B'
1. Copper	a. Low melting point
2. Sodium	b. Liquid
3. Magnesium	c. High melting point
4. Boron	d. Conduction of heat
	e. 2, 8, 2

Answer:

Column 'A'	Column 'B'
1. Copper	d. Conduction of heat
2. Sodium	a. Low melting point
3. Magnesium	e. 2, 8, 2
4. Boron	c. High melting point

In simple words: This match the columns question links elements to their characteristic properties or electronic configurations. Copper is known for heat conduction, sodium for its low melting point, magnesium for its electronic configuration (2,8,2), and boron for its high melting point.

🎯 Exam Tip: Pay close attention to distinguishing characteristics. Copper's excellent thermal conductivity is a key property, while sodium's low melting point and magnesium's electron shell arrangement are specific attributes often tested. Boron, as a metalloid, often has a higher melting point than typical non-metals.

Define The Following:

Question 1. Define Ductility.
Answer: The property due to which a substance can be drawn into a thin wire is called ductility.
In simple words: Ductility describes how easily a material can be stretched into a thin wire without breaking. Metals like copper are highly ductile.

🎯 Exam Tip: Understanding ductility helps explain why metals are used for electrical wiring. Distinguish it from malleability.

Question 2. Define Malleability.
Answer: The property due to which a substance can be hammered into a thin sheet is called malleability.
In simple words: Malleability is the ability of a material to be flattened into thin sheets by hammering or rolling without cracking. Gold is a highly malleable metal.

🎯 Exam Tip: Malleability and ductility are key physical properties of metals. Give examples to illustrate your definitions.

Question 3. Define Metalloids.
Answer: The element which shows the properties of metals as well as those of non-metals is called a metalloid.
In simple words: Metalloids are elements that have properties intermediate between metals and non-metals, such as silicon or germanium.

🎯 Exam Tip: Remember that metalloids are found on the "staircase" line in the periodic table. Silicon is a common example.

Question 4. Define Corrosion.
Answer: Gases in the air react with metals in presence of moisture to form metal compounds on its surface, this destroys the metal gradually and is called corrosion.
In simple words: Corrosion is the gradual deterioration of a metal due to its reaction with elements in its environment, especially oxygen and moisture, leading to the formation of compounds like rust.

🎯 Exam Tip: Focus on the conditions required for corrosion (air/oxygen, moisture) and its impact on metal properties. Include common examples like rusting of iron.

Question 5. Define Alloy.
Answer: A homogeneous mixture of two or more metals or a homogeneous mixture of metal with non-metals is called alloy.
In simple words: An alloy is a mixture made by combining two or more metals, or a metal with a non-metal, to create a new material with enhanced properties, like strength or corrosion resistance.

🎯 Exam Tip: Provide examples of common alloys (brass, bronze, steel) and explain why they are useful, emphasizing improved properties compared to pure metals.

Answer The Following Questions In One Sentence:

Question 1. Name an alloy of copper and tin.
Answer: An alloy of copper and tin is termed as bronze.
In simple words: Bronze is the alloy created by mixing copper and tin.

🎯 Exam Tip: Knowing common alloys and their constituent metals is important. Bronze is a historically significant alloy.

Question 2. Name a metal which is in liquid state at ordinary temperature.
Answer: Mercury is in liquid state at ordinary temperature.
In simple words: Mercury is a unique metal because it remains liquid at room temperature.

🎯 Exam Tip: Mercury is an important exception to the general rule that metals are solid at room temperature. Note its use in thermometers.

Question 3. Name two metals which are malleable.
Answer: Iron and aluminium are malleable metals.
In simple words: Iron and aluminium are metals that can be hammered into different shapes and thin sheets without breaking.

🎯 Exam Tip: Provide common examples of malleable metals. Explain how this property makes them useful in manufacturing.

Question 4. Name two metals which are ductile.
Answer: Gold and silver are ductile metals.
In simple words: Gold and silver are metals that can be drawn into very fine wires.

🎯 Exam Tip: Recall that ductility allows metals to be drawn into wires. Gold is known for its extreme ductility.

Question 5. Name two metals which are good conductors of heat.
Answer: Silver and copper are good conductors of heat.
In simple words: Silver and copper are highly efficient at transferring heat, making them useful in cookware and heat exchangers.

🎯 Exam Tip: Good thermal conductivity is a characteristic property of metals. Provide examples relevant to daily life, like cooking utensils.

Question 6. Name two metals which are good conductors of electricity.
Answer: Copper and aluminium are good conductors of electricity.
In simple words: Copper and aluminium allow electric current to pass through them easily, making them suitable for electrical wires.

🎯 Exam Tip: Good electrical conductivity is another key metallic property. Copper is widely used for electrical wiring due to this.

Question 7. Name two non-metals which are in solid state at room temperature.
Answer: Carbon and sulphur are solids at room temperature.
In simple words: Unlike most non-metals which are gases, carbon (in forms like diamond or graphite) and sulphur are solid at ordinary temperatures.

🎯 Exam Tip: Remember the common states of matter for elements at room temperature. Identify exceptions, such as solid non-metals.

Question 8. Name two non-metals which are in gaseous state at room temperature.
Answer: Hydrogen and oxygen are in gaseous state at room temperature.
In simple words: Hydrogen and oxygen are examples of non-metals that naturally exist as gases at typical room temperatures.

🎯 Exam Tip: Most non-metals are gases or solids at room temperature, with very few being liquid (like bromine).

Question 9. Name the non-metal having electrical conductivity.
Answer: Graphite has electrical conductivity.
In simple words: Graphite, a form of carbon, is an unusual non-metal because it can conduct electricity, unlike most other non-metals.

🎯 Exam Tip: Graphite is an important exception to the rule that non-metals are poor conductors of electricity. Explain why (presence of free electrons).

Question 10. Name two non-metals which are lustrous.
Answer: Iodine and diamond are lustrous in nature.
In simple words: Iodine and diamond are non-metals that exhibit a shiny appearance, which is typically a property of metals.

🎯 Exam Tip: Remember these exceptions to the general properties of non-metals. Lustre is usually a metallic property, but some non-metals like diamond also show it.

Question 11. Name two non-metals having high melting points.
Answer: Carbon and boron melt at high temperature.
In simple words: Carbon (especially diamond and graphite) and boron are non-metals that require very high temperatures to melt.

🎯 Exam Tip: While many non-metals have low melting points, some, like carbon in its various allotropes, have exceptionally high melting points due to strong covalent bonding.

Question 12. State two metals which can be cut easily with a knife.
Answer: Sodium and potassium are soft metals and can be cut easily with a knife.
In simple words: Sodium and potassium are very soft alkali metals, unlike most hard metals, and can be easily sliced.

🎯 Exam Tip: Sodium and potassium are key examples of alkali metals known for their softness and high reactivity. Mention their placement in the periodic table.

Question 13. Which is the hardest natural substance?
Answer: Diamond, which is a form of carbon is the hardest natural substance.
In simple words: Diamond, a naturally occurring form of the non-metal carbon, is the toughest material found on Earth.

🎯 Exam Tip: Diamond's hardness is due to its strong covalent bonding structure. This is an important property for this allotrope of carbon.

Question 14. State the property of the metals for which they can be drawn into wires.
Answer: The property of the metals due to which they can be drawn into wires is called ductility.
In simple words: The ability of metals to be stretched and pulled into thin wires without breaking is known as ductility.

🎯 Exam Tip: Clearly define ductility and connect it to practical applications like electrical wiring. Differentiate it from malleability.

Question 15. State the property of the metals due to which they can be beaten into thin sheets.
Answer: The property of the metals due to which they can be beaten into thin sheets is called malleability.
In simple words: Malleability is the characteristic that allows metals to be flattened into thin sheets by hammering or rolling.

🎯 Exam Tip: Define malleability and provide common examples such as aluminum foil. Contrast it with ductility.

Question 16. Which of the following metals react with cold water? Sodium, iron, copper, potassium.
Answer: Sodium and potassium metals react with cold water.
In simple words: Highly reactive metals like sodium and potassium readily react with cold water, producing hydrogen gas and heat.

🎯 Exam Tip: Remember the reactivity series of metals. Alkali metals (Sodium, Potassium) are very reactive and react vigorously with cold water.

Question 17. Which of the following metals do not react with cold water or hot water?
Answer: Aluminium and iron do not react with cold water or hot water.
In simple words: Aluminium and iron are less reactive metals that do not react with water, whether cold or hot, but might react with steam under specific conditions.

🎯 Exam Tip: Understand the varying reactivity of metals with water. Some react with cold, some with hot, and others only with steam or not at all.

Question 18. What are the constituents of stainless steel?
Answer: Iron with carbon, chromium and nickel are the constituents of stainless steel.
In simple words: Stainless steel is an alloy primarily made of iron, enhanced with carbon for strength, and chromium and nickel for corrosion resistance.

🎯 Exam Tip: Knowing the composition of common alloys like stainless steel is important for understanding their properties and applications.

Question 19. State the term used to express the purity of gold.
Answer: The purity of gold is expressed in carat.
In simple words: The fineness or purity of gold is measured using a unit called a carat.

🎯 Exam Tip: Understand the carat system (e.g., 24-carat is pure gold) and its practical implications for jewelry making.

Question 20. Name two metals having low melting points and boiling points.
Answer: Sodium and potassium having low melting points and boiling points.
In simple words: Sodium and potassium are metals that melt and boil at relatively low temperatures compared to most other metals.

🎯 Exam Tip: While most metals have high melting points, alkali metals like sodium and potassium are exceptions, being soft and having low melting points.

Question 21. Name a non-metal which is in liquid state at room temperature.
Answer: Bromine is in liquid state at room temperature.
In simple words: Bromine is a non-metal that exists as a reddish-brown liquid at normal room temperatures.

🎯 Exam Tip: Bromine is the only non-metal that is liquid at room temperature; it's an important exception to remember.

Question 22. State the atomic number and electronic configuration of sodium.
Answer: Atomic number of sodium: 11.
Electronic configuration of sodium (Na): 2, 8, 1.
In simple words: Sodium has an atomic number of 11, meaning it has 11 protons and 11 electrons, with its electrons arranged in shells as 2, 8, and 1.

🎯 Exam Tip: Practice writing electronic configurations for elements up to atomic number 20. The valence electrons (here, 1) determine chemical reactivity.

Question 23. State the atomic number and electronic configuration of aluminium.
Answer: Atomic number of aluminium: 13.
Electronic configuration of aluminium (Al): 2, 8, 3.
In simple words: Aluminium has an atomic number of 13, with its 13 electrons distributed in shells as 2, 8, and 3, indicating 3 valence electrons.

🎯 Exam Tip: Electronic configuration is fundamental to understanding an element's chemical behavior, especially its tendency to form ions.

Question 24. Give two example of metalloids.
Answer: Metalloids: Arsenic (As),
germanium (Ge), antimony (Sb).
In simple words: Metalloids are elements like Arsenic, Germanium, and Antimony that exhibit properties characteristic of both metals and non-metals.

🎯 Exam Tip: Provide at least two clear examples of metalloids. Remember their position on the periodic table as a 'staircase' separating metals and non-metals.

Question 25. State the atomic number and electronic configuration of nitrogen.
Answer: Atomic number of nitrogen: 7.
Electronic configuration of nitrogen (N): 2, 5.
In simple words: Nitrogen has an atomic number of 7, meaning it has 7 protons and 7 electrons, configured with 2 electrons in the first shell and 5 in the outermost shell.

🎯 Exam Tip: For non-metals like nitrogen, their electronic configuration, particularly the valence electrons, helps predict their tendency to gain electrons and form negative ions.

Answer The Following Questions:

Question 1. A metal can be drawn into a wire. Explain why.
Answer:
1. The property due to which a substance can be drawn into a thin wire is called ductility.
2. Metals are ductile. Thus, a metal can be draw into a wire.
In simple words: Metals can be shaped into wires because they possess the property of ductility, which allows them to be stretched without breaking.

🎯 Exam Tip: Define ductility accurately and explain its direct application in wire drawing. Provide common examples of ductile metals.

Question 2. A metal can be hammered into a thin sheet. Explain why.
Answer:
1. The property due to which a substance can be hammered (or rolled) into a thin sheet without cracking is called malleability.
2. Metals are malleable. Thus, a metal can be hammered to form a thin sheet.
In simple words: Metals can be flattened into thin sheets because they are malleable, meaning they can be hammered or rolled without fracturing.

🎯 Exam Tip: Clearly define malleability and give practical examples like aluminum foil. Differentiate it from ductility, as both relate to a metal's ability to be reshaped.

Question 3. State the properties of metals.
Answer:
1. Metals have a lustre.
2. Metals are malleable. They can be beaten into thin sheets.
3. Metals are ductile. They can be drawn into wires.
4. They are good conductors of heat and electricity.
5. At ordinary temperature, metals are generally solid. (Exception: Mercury is liquid.)
6. Metals usually have high density.
In simple words: Metals typically have a shiny appearance, can be hammered into sheets or drawn into wires, conduct heat and electricity well, are usually solid at room temperature (except mercury), and have high density.

🎯 Exam Tip: List at least 5-6 distinct properties of metals. Remember common exceptions like mercury (liquid) and sodium/potassium (soft).

Question 4. State the properties of non-metals.
Answer:
1. Non-metals lack lustre.
2. As non-metals are brittle, they are not malleable.
3. They are not ductile.
4. Non-metals are poor conductors of heat and electricity.
5. At ordinary temperature, non-metals are in the solid or gaseous state. (Exception: Bromine is liquid.)
6. Non-metals have low density in the solid state.
In simple words: Non-metals generally lack shine, are brittle, cannot be drawn into wires or hammered into sheets, are poor conductors of heat and electricity, exist as solids or gases at room temperature (except bromine), and have low density in solid form.

🎯 Exam Tip: Contrast the properties of non-metals with those of metals. Highlight key exceptions like graphite (conducts electricity) and iodine/diamond (lustrous).

Question 5. How are metal ions formed? Give two examples.
Answer: Metals have a tendency to lose their valence electrons to form positively charged ions, called cations.
Examples:
\( \text{Na (2, 8, 1)} \implies \text{Na}^+ \text{ (2, 8)} + \text{1e}^- \)
Sodium \( \qquad \) Sodium ion
\( \text{Mg (2, 8, 2)} \implies \text{Mg}^{++} \text{ (2, 8)} + \text{2e}^- \)
Magnesium \( \qquad \) Magnesium ion
\( \text{Al (2, 8, 3)} \implies \text{Al}^{+++} \text{ (2, 8)} + \text{3e}^- \)
Aluminium \( \qquad \) Aluminium ion
In simple words: Metal atoms form positively charged ions, called cations, by giving up their outermost electrons to achieve a stable electron configuration.

🎯 Exam Tip: Understand that metals lose electrons to form positive ions (cations). Use electronic configurations to illustrate how many electrons are lost and why.

Question 6. Classify the following elements into metals and non-metals : Silicon, gold, silver, sulphur, carbon, aluminium, copper and phosphorus.
Answer:
Metals: Gold, silver, aluminium and copper.
Non-metals: Silicon, sulphur, carbon and phosphorus.
In simple words: Elements are categorized as metals or non-metals based on their characteristic properties, with gold, silver, aluminum, and copper being metals, while silicon, sulfur, carbon, and phosphorus are non-metals.

🎯 Exam Tip: Be able to classify common elements based on their known properties. Remember that silicon is a metalloid, often grouped with non-metals for some properties.

Question 7. How are metal oxides formed? Explain with an example.
Answer: Metals combine with oxygen in the air to form their oxides.
Metal + Oxygen \( \implies \) Metal oxide
When magnesium burns in air, it combines with oxygen to form magnesium oxide.
\( \text{2Mg} + \text{O}_2 \implies \text{2MgO} \)
Magnesium \( \qquad \) Oxygen \( \qquad \) Magnesium oxide
In simple words: Metal oxides are formed when metals react with oxygen, typically from the air, during processes like burning or slow corrosion. For example, magnesium reacts with oxygen to form magnesium oxide.

🎯 Exam Tip: Write balanced chemical equations for the formation of metal oxides. Remember that most metal oxides are basic in nature.

Question 8. How will you show that metal oxides are basic in nature?
Answer:
1. Take magnesium oxide in a test tube. Add water in the test-tube. Shake the test-tube. Test the solution with red and blue litmus paper. Blue litmus paper remains as it is while red litmus paper turns blue. This shows that metal oxides are basic in nature.
2. Metal oxides react with an acid to form salt and water. Therefore, metal oxides are basic in nature.
Metal oxide + Acid \( \implies \) Salt + Water
\( \text{MgO} + \text{2HCl} \implies \text{MgCl}_2 + \text{H}_2\text{O} \)
Magnesium oxide \( \qquad \) Hydrochloric acid \( \qquad \) Magnesium chloride (Salt)
In simple words: Metal oxides are basic because they turn red litmus paper blue when dissolved in water and react with acids to form salt and water.

🎯 Exam Tip: Remember the litmus test for bases (red to blue) and the neutralization reaction with acids. Use a clear example like magnesium oxide with HCl.

Question 9. How do metals react with acid? Explain with an example.
Answer: The metals react with dilute acids to form metal salts. Metals liberate hydrogen gas from dilute acids.
Metal + Dilute acid \( \implies \) Metal salt + Hydrogen gas.
Magnesium reacts with dilute HCl to form magnesium chloride and hydrogen gas.
\( \text{Mg} + \text{2HCl} \implies \text{MgCl}_2 + \text{H}_2\uparrow \)
Magnesium \( \qquad \) Magnesium chloride \( \qquad \) Hydrogen
In simple words: Metals typically react with dilute acids to produce a metal salt and hydrogen gas, as seen when magnesium reacts with hydrochloric acid.

🎯 Exam Tip: Remember that active metals react with dilute acids to displace hydrogen. The "pop" sound test confirms the presence of hydrogen gas.

Question 10. How do metals react with water? Explain with an example.
Answer: Most metals do not react with cold water. But some metals like sodium and potassium react with cold water to form their hydroxides and hydrogen gas.
Sodium reacts with water to form sodium hydroxide.
\( \text{2Na} + \text{2H}_2\text{O} \implies \text{2NaOH} + \text{H}_2\uparrow \)
Sodium \( \qquad \) Sodium hydroxide
In simple words: Sodium reacts vigorously with water to produce sodium hydroxide and hydrogen gas, often releasing enough heat to ignite the hydrogen.

🎯 Exam Tip: Note the extreme reactivity of sodium with water. This reaction is highly exothermic and produces hydrogen gas.

Question 11. How do non-metals react with oxygen? Explain with an example.
Answer: Non-metals combine with oxygen to form their oxides.
Non-metal + Oxygen \( \implies \) Non-metal oxide
When carbon burns in air, it combines with oxygen to form carbon dioxide.
\( \text{C} + \text{O}_2 \implies \text{CO}_2 \)
Carbon \( \qquad \) Carbon dioxide
In simple words: Non-metals react with oxygen to form non-metal oxides, which are typically acidic. For example, carbon burns in air to produce carbon dioxide.

🎯 Exam Tip: Remember that non-metal oxides are generally acidic. Write balanced equations for the reaction of common non-metals with oxygen.

Question 12. How will you show that non-metal oxides are acidic in nature?
Answer:
1. Take non-metal oxide in a test tube. Add water in the test tube. Test the solution with blue and red litmus paper. Red litmus paper remains as it is while blue litmus paper turns red. This shows that non-metal oxides are acidic in nature.
2. The oxides of non-metals are acidic in nature. They react with bases to form soluble salt and water. Therefore, non-metal oxides are acidic in nature.
\( \text{C} + \text{O}_2 \implies \text{CO}_2 \)
\( \text{CO}_2 + \text{2NaOH} \implies \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} \)
In simple words: Non-metal oxides are acidic because their solutions turn blue litmus paper red and they react with bases to form salt and water, as demonstrated by carbon dioxide.

🎯 Exam Tip: Understand the litmus test for acids (blue to red) and the neutralization reaction with bases. Use common non-metal oxides like CO2 and SO2 as examples.

Question 13. How are non-metal ions formed? Give two examples.
Answer: Non-metals have a tendency to accept electrons in their valence shell to form negatively charged ions called anions.
Examples:
\( \text{Cl (2, 8, 7)} + \text{e}^- \implies \text{Cl}^- \text{ (2, 8, 8)} \)
Chlorine \( \qquad \) Chloride ion
\( \text{O (2, 6)} + \text{2e}^- \implies \text{O}^{--} \text{ (2, 8)} \)
Oxygen \( \qquad \) Oxide ion
\( \text{N (2, 5)} + \text{3e}^- \implies \text{N}^{---} \text{ (2, 8)} \)
Nitrogen \( \qquad \) Nitride ion
In simple words: Non-metal atoms gain electrons into their outer shell to form negatively charged ions called anions, achieving a stable electron configuration.

🎯 Exam Tip: Explain that non-metals gain electrons to form negative ions (anions). Illustrate with electronic configurations and the number of electrons gained.

Question 14. What is meant by noble metals? Give two examples.
Answer: Some metals like gold, silver, platinum, palladium and rhodium are found in nature in the form of elements. They are not affected by air, water, acids and heat etc. Hence, they are called noble metals.
In simple words: Noble metals are elements such as gold and platinum that are highly resistant to corrosion and oxidation, meaning they do not easily react with air, water, or acids.

🎯 Exam Tip: Focus on the inertness and lack of reactivity as defining characteristics of noble metals. Provide at least two common examples.

Give Scientific Reasons:

Question 1. Ornaments are generally not made from 24-carat gold.
Answer:
1. 24-carat pure gold is considered as gold of 100% purity.
2. 24-carat pure gold is very soft. 100% pure gold breaks due to pressure or gets bent easily. Therefore, ornaments are generally not made from 24-carat gold.
In simple words: 24-carat gold is too soft for making durable ornaments as it can easily deform or break under pressure, so it is usually alloyed with other metals to increase its hardness.

🎯 Exam Tip: Explain the concept of carat purity and relate it to the physical properties (softness) of pure gold, justifying why alloys are preferred for jewelry.

Question 2. Ships are painted at frequent intervals.
Answer:
1. The metal sheets of ships are made from iron.
2. Due to salty seawater, the metal sheets of ships get rusted and corroded. Paints contain metals like zinc or magnesium. This prevents the metal surface of the ship coming into direct contact with salty seawater. Therefore, ships are painted at frequent intervals.
In simple words: Ships are regularly painted to prevent their iron hulls from rusting and corroding in salty seawater, as the paint acts as a protective barrier.

🎯 Exam Tip: Emphasize the corrosive effect of salty water on iron. Explain how painting acts as a protective layer and prevents the metal from coming into contact with oxygen and moisture.

Question 3. Gold and platinum are called noble elements.
Answer:
1. The metals such as gold and platinum are found in nature in the form of elements.
2. They are not affected by water, air, acids, heat and also do not take part in chemical reactions. Hence, they are called noble metals.
In simple words: Gold and platinum are termed noble elements because they are highly unreactive and resist corrosion, existing in their elemental form in nature without easily reacting with other substances.

🎯 Exam Tip: Define noble metals by their chemical inertness and resistance to environmental factors. Use examples like gold and platinum.

Explain The Following Reactions With The Help Of Balanced Equations:

Question 1. Magnesium combines with oxygen.
Answer: Magnesium combines with oxygen to form magnesium oxide.
\( \text{2Mg} + \text{O}_2 \implies \text{2MgO} \)
Magnesium \( \qquad \) Oxygen \( \qquad \) Magnesium oxide
In simple words: When magnesium reacts with oxygen, it forms magnesium oxide, an example of a metal reacting with air.

🎯 Exam Tip: Write the balanced chemical equation clearly. Remember to include the states of matter if known, though not explicitly asked here.

Question 2. Magnesium oxide reacts with dilute HCl.
Answer: When magnesium oxide reacts with dilute HCl, magnesium chloride (salt) and water are formed.
\( \text{MgO} + \text{2HCl} \implies \text{MgCl}_2 + \text{H}_2\text{O} \)
Magnesium oxide \( \qquad \) Dilute hydrochloric acid \( \qquad \) Magnesium chloride (Salt)
In simple words: Magnesium oxide, a basic oxide, reacts with hydrochloric acid to produce magnesium chloride salt and water, which is a neutralization reaction.

🎯 Exam Tip: Remember that metal oxides are generally basic and react with acids to form salt and water. Write the balanced equation correctly.

Question 3. Magnesium reacts with dilute HCl.
Answer: When magnesium reacts with dil. hydrochloric acid, magnesium chloride is formed and hydrogen gas is evolved.
\( \text{Mg(s)} + \text{2HCl(aq)} \implies \text{MgCl}_2 \text{(aq)} + \text{H}_2 \text{(g)} \)
Magnesium \( \qquad \) Magnesium chloride \( \qquad \) Hydrogen
In simple words: Magnesium metal reacts with dilute hydrochloric acid to yield magnesium chloride solution and release hydrogen gas.

🎯 Exam Tip: This is a typical displacement reaction where a more reactive metal (magnesium) displaces hydrogen from an acid. Balance the equation and include states of matter.

Question 4. Sodium reacts with water.
Answer: When sodium reacts with water, sodium hydroxide and hydrogen gas are formed.
\( \text{2Na} + \text{2H}_2\text{O} \implies \text{2NaOH} + \text{H}_2\uparrow \)
Sodium \( \qquad \) Sodium hydroxide
In simple words: Sodium reacts vigorously with water to produce sodium hydroxide and hydrogen gas, often releasing enough heat to ignite the hydrogen.

🎯 Exam Tip: Note the extreme reactivity of sodium with water. This reaction is highly exothermic and produces hydrogen gas.

Question 5. Carbon burns in air.
Answer: When carbon burns in air, carbon dioxide is formed.
\( \text{C} + \text{O}_2 \implies \text{CO}_2 \)
Carbon \( \qquad \) Carbon dioxide
In simple words: When carbon is burned in the presence of air (oxygen), it combines to form carbon dioxide gas.

🎯 Exam Tip: This is a common combustion reaction. Remember that carbon dioxide is a non-metal oxide and is acidic in nature.

Question 6. Carbon dioxide reacts with sodium hydroxide.
Answer: When carbon dioxide reacts with sodium hydroxide, soluble salt sodium carbonate and water are formed.
\( \text{CO}_2 + \text{2NaOH} \implies \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} \)
Carbon dioxide \( \qquad \) Sodium hydroxide \( \qquad \) Sodium carbonate
In simple words: Carbon dioxide, an acidic oxide, reacts with the base sodium hydroxide to produce sodium carbonate (a salt) and water in a neutralization reaction.

🎯 Exam Tip: This reaction demonstrates the acidic nature of non-metal oxides reacting with a strong base to form salt and water. Ensure the equation is balanced.

Question 7. Carbon dioxide reacts with water.
Answer: When carbon dioxide reacts with water, carbonic acid is formed.
\( \text{CO}_2 + \text{H}_2\text{O} \implies \text{H}_2\text{CO}_3 \)
Carbon dioxide \( \qquad \) Carbonic acid
In simple words: Carbon dioxide dissolves in water to form carbonic acid, which is a weak acid.

🎯 Exam Tip: This reaction is important for understanding acid rain and the carbonation of beverages. Note the reversible nature of this reaction.

Question 8. Sulphur dioxide reacts with water.
Answer: When sulphur dioxide reacts with water, sulphurous acid is formed.
\( \text{SO}_2 \text{(g)} + \text{H}_2\text{O} \implies \text{H}_2\text{SO}_3 \)
Sulphur dioxide \( \qquad \) Sulphurous acid
In simple words: Sulphur dioxide gas reacts with water to create sulphurous acid, contributing to acid rain.

🎯 Exam Tip: This reaction illustrates another acidic non-metal oxide reacting with water. Write the balanced equation and identify the product acid.

Question 9. Sulphur trioxide reacts with water.
Answer: When sulphur trioxide reacts with water, sulphuric acid is formed.
\( \text{SO}_3 \text{(g)} + \text{H}_2\text{O} \implies \text{H}_2\text{SO}_4 \)
Sulphur trioxide \( \qquad \) Sulphuric acid
In simple words: Sulphur trioxide reacts with water to produce sulphuric acid, a strong acid and a major component of acid rain.

🎯 Exam Tip: This is a crucial reaction in the formation of sulphuric acid. Recognize it as a non-metal oxide reacting with water to form an acid.

Write Short Notes:

Question 1. The noble metals.
Answer: Some metals like gold, silver, platinum, palladium and rhodium are found in nature in the form of elements. They are not affected by air, water, acids and heat etc. Hence, they are called noble metals.
Uses of Noble Metals:
1. Gold, silver and platinum are used to prepare ornaments.
2. Silver is used in medicines. (It has antibacterial property).
3. Gold and silver are also used to make metals and few electronic devices.
4. Platinum, palladium metals are used as catalyst.
In simple words: Noble metals like gold, silver, and platinum are highly unreactive and found in their pure form, valued for jewelry, medicine, electronics, and as catalysts due to their stability.

🎯 Exam Tip: Define noble metals based on their inertness and list their primary uses, highlighting their resistance to corrosion and catalytic properties.

Question 2. The purity of gold.
Answer:
1. The purity of gold is measured in carats.
2. Twenty-four carat gold is considered as gold of 100% purity.
3. 24-carat pure gold is very soft. 100% pure gold bends easily or breaks due to pressure. Therefore, copper or silver is added to gold in the necessary proportion (while making ornaments).
4. Generally, 22-carat gold is used in making ornaments.

Percentage of gold	Carat
100%	24
91.66%	22
75%	18
58.33%	14
50%	12
41.66%	10

In simple words: Gold purity is expressed in carats, where 24-carat is pure gold, but it's often mixed with other metals to create alloys like 22-carat gold, which is harder and more suitable for jewelry.

🎯 Exam Tip: Understand the carat system and why gold is typically alloyed for ornaments. Be able to associate common carat values with their percentage purity.

Distinguish Between The Following:

Question 1. Metals and Non-metals
Answer:

Metals	Non-metals
1. Metals have lustre.	1. Non-metals do not have lustre.
2. Metals are malleable.	2. Non-metals are not malleable.
3. Metals are ductile.	3. Non-metals are not ductile.
4. Metals are good conductors of heat and electricity.	4. Non-metals are poor conductors of heat and electricity.
5. At room temperature, metals are in the solid state. (Exception - Mercury is liquid.)	5. At room temperature, non-metals are in the solid, or gaseous state. (Exception Bromine. It is in liquid state.)
6. Generally, metals have high densities.	6. Generally, non-metals have lower densities.

In simple words: Metals are typically shiny, solid, malleable, ductile, and good conductors of heat and electricity, with high densities. Non-metals generally lack these properties, being dull, often brittle, non-ductile, poor conductors, and can exist as solids, liquids, or gases with lower densities.

🎯 Exam Tip: Focus on understanding the contrasting physical and chemical properties of metals and non-metals, as this is a fundamental concept for classification and can earn full marks in comparison questions.