CBSE Class 10 Chemistry Metals And Non Metals Worksheet Set D

Question. Aqua regia is called as royal water because it dissolves gold its composition is 1:3 concentrated.
(a) H₂SO4: HNO₃
(b) HNO₃: H₂SO₄
(c) HNO₃: HCl
(d) HCl: HNO₃

Answer: C

Question. Alloys are homogenous mixtures of a metal with a metal or non-metal. Which of the following alloys contain non-metal as one of its constituents.
(a) Brass
(b) Bronze
(c) amalgam
(d) stainless steel.

Answer: D

Question. Assertion: Nitrogen is a non-metal.
Reason: Nitrogen has 5 valance electrons.
(a) Both A and R are true and R is correct explanation for A.
(b) Both A and R are true and R is not the correct explanation for A.
(c) A is true but R is false.
(d) A is false but R is true. 

Answer: B

Question.Which of the following is a liquid non-metal at room temperature:
(a) Mercury
(b)Bromine
(c)Chlorine
(d) Sulphur

Answer: B

Question. Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) all of the above. 

Answer: C

Question. Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin.
(b) zinc has a higher melting point than tin.
(c) zinc is more reactive than tin.
(d) zinc is less reactive than tin.

Answer: C

Question. Which of the following is not an ionic compound.
(a) KCl
(b) MgCl₂
(c) CCl₄
(d) NaCl

Answer: C

Question. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
(a) calcium
(b) carbon
(c) silicon
(d) iron 

Answer: A

Question. Which of the following pairs will give displacement reactions?
(a) NaCl solution and copper metal
(b) MgCl₂ solution and aluminium metal
(c) FeSO₄ solution and silver metal
(d) AgNO₃ solution and copper metal. 

Answer: D

Question. Assertion: Zinc oxide is amphoteric in nature.
Reason: Zinc oxide reacts with both acids and bases.
(a) Both A and R are true and R is correct explanation for A.
(b) Both A and R are true and R is not the correct explanation for A.
(c) A is true but R is false.
(d) A is false but R is true. 

Answer: C

Question. Which one of the following four metals would be displaced form the solution of its salt by other three metals?
(a) Mg
(b) Ag
(c) Zn
(d) Cu

Answer: B

Question. Which metals do not corrode easily?
Answer. More reactive a metal is, more likely it is to be corroded. Therefore, less reactive metals are less likely to get corroded. This is why gold plating provides high resistance to corrosion.

Question. Why is sodium kept immersed in kerosene oil? 
Answer. Sodium and potassium are very reactive metals and and combine explosively with air as well as water. Hence, they catch fire if kept in open. Therefore, to prevent accidental fires and accidents, sodium is stored immersed in kerosene oil. 

Question. You are given a hammer, a battery, a bulb, wires and a switch.
(a) How could you use them to distinguish between samples of metals and non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and nonmetals.
Answer. (a) With the hammer, we can beat the sample and if it can be beaten into thin sheets (that is, it is malleable), then it is a metal otherwise a non-metal. Similarly, we can use the battery, bulb, wires, and a switch to set up a circuit with the sample. If the sample conducts electricity, then it is a metal otherwise a non-metal.
(b) The above tests are useful in distinguishing between metals and non-metals as these are based on the physical properties. No chemical reactions are involved in these tests.

Question. What are amphoteric oxides? Give two examples of amphoteric oxides. 
Answer. Those oxides that behave as both acidic and basic oxides are called amphoteric oxides.
Examples: aluminium oxide (Al₂O₃), zinc oxide (ZnO) 

Question. Explain the meanings of malleable and ductile.
Answer.  Malleable: Substances that can be beaten into thin sheets are called malleable. For example, most of the metals are malleable.
Ductile: Substances that can be drawn into thin wires are called ductile. For example, most of the metals are ductile.

 Question. Name two metals which are found in nature in the free state.
Answer. The metals at the bottom of the reactivity series are mostly found in free state. For example: gold, silver, and platinum. 

Question. Give an example of a metal which
(i) is a liquid at room temperature.
(ii) can be easily cut with a knife.
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat.
Answer. 
(i) Metal that exists in liquid state at room temperature → Mercury
(ii) Metal that can be easily cut with a knife → Sodium
(iii) Metal that is the best conductor of heat → Silver
(iv) Metals that are poor conductors of heat → Mercury and lead

Question. State two ways to prevent the rusting of iron. 
Answer. Two ways to prevent the rusting of iron are:
(i) Oiling, greasing, or painting: By applying oil, grease, or paint, the surface becomes water proof and the moisture and oxygen present in the air cannot come into direct contact with iron. Hence, rusting is prevented.
(ii) Galvanisation: An iron article is coated with a layer of zinc metal, which prevents the iron to come in contact with oxygen and moisture. Hence, rusting is prevented.

Question. Give reasons
(a) Platinum, gold and silver are used to make jewellery.
(b) Sodium, potassium and lithium are stored under oil.
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
Answer. (a) Platinum, gold, and silver are used to make jewellery because they are very lustrous. Also, they are very less reactive and do not corrode easily.
(b) Sodium, potassium, and lithium are very reactive metals and react very vigorously with air as well as water. Therefore, they are kept immersed in kerosene oil in order to prevent their contact with air and moisture.
(c) Though aluminium is a highly reactive metal, it is resistant to corrosion. This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide. This oxide layer is very stable and prevents further reaction of aluminium with oxygen. Also, it is light in weight and a good conductor of heat. Hence, it is used to make cooking utensils.
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction because metals can be easily extracted from their oxides rather than from their carbonates and sulphides.

Question. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
Answer. Copper reacts with moist carbon dioxide in air to form copper carbonate and as a result, copper vessel loses its shiny brown surface forming a green layer of copper carbonate.
The citric acid present in the lemon or tamarind neutralises the basis copper carbonate and dissolves the layer. That is why, tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic lustre. 

Question. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Answer. In the electrolytic refining of a metal M:
Anode → Impure metal M
Cathode → Thin strip of pure metal M
Electrolyte → Solution of salt of the metal M

Question. What are alloys?
Answer. Alloys are homogeneous mixtures of two or more elements. The elements could be two metals, or a metal and a non-metal. An alloy is formed by first melting the metal and then dissolving the other elements in it. For example, steel is an alloy of iron and carbon. 

Question. Why do ionic compounds have high melting points?
Answer. Ionic compounds have strong electrostatic forces of attraction between the ions. Therefore, it requires a lot of energy to overcome these forces. That is why ionic compounds have high melting points.

Question. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer.  Metals that are more reactive than hydrogen displace it from dilute acids. For example: sodium and potassium. Metals that are less reactive than hydrogen do not displace it. For example: copper and silver.

Question. A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
Answer. He must have dipped the gold metal in the solution of aqua regia − a 3:1 mixture of conc. HCl and conc. HNO₃. Aqua regia is a fuming, highly corrosive liquid. It dissolves gold in it. After dipping the gold ornaments in aqua regia, the outer layer of gold gets dissolved and the inner shiny layer appears. That is why the weight of gold ornament reduced.