CBSE Class 10 Chemistry Metals And Non Metals Worksheet Set 14

This Class 10 Chemistry worksheet, Set 14, has 20 short questions with answers from Chapter 3, Metals and Non-metals, and prints well on two sides of a sheet. It has ten fill in the blanks followed by ten very short answer questions on physical properties, occurrence, reactions of metals and ionic bonding.

Fill in the Blanks

Question 1. The most abundant metal found in earth crust is _________.
Answer:
Aluminium. It makes up about 7 to 8 per cent of the Earth’s crust.
In simple words: Aluminium is the most plentiful metal in the earth’s crust.

Teacher's Note:
1. Do not mix up the most abundant metal (aluminium) with the most abundant element (oxygen).
2. Iron is the second most abundant metal.

Question 2. _________ is a non-metal which has a very high melting and boiling point.
Answer:
Carbon (as diamond or graphite). Most non-metals have low melting and boiling points; carbon is the exception.
In simple words: Carbon is the high-melting exception among non-metals.

Teacher's Note:
1. Diamond and graphite are allotropes of carbon.
2. Learn exceptions in a table.

Question 3. _________ is a non-metal which is lustrous.
Answer:
Iodine is a shiny (lustrous) non-metal. Most non-metals are dull.
In simple words: Iodine crystals shine like a metal.

Teacher's Note:
1. Graphite is also lustrous.
2. Lustre alone does not prove that an element is a metal.

Question 4. The element which can be easily cut with knife are _________ and _________.
Answer:
Sodium and potassium are so soft that they can be cut with a knife.
In simple words: Sodium and potassium are soft metals.

Teacher's Note:
1. Most metals are hard; these are soft exceptions.
2. They are stored under kerosene.

Question 5. At room temperature, one metal that is present in liquid state is _________.
Answer:
Mercury. (Bromine is the only liquid non-metal.)
In simple words: Mercury is the liquid metal.

Teacher's Note:
1. Gallium and caesium melt just above room temperature.
2. Mercury is used in thermometers.

Question 6. Metal reacts with water to produce _________ and hydrogen gas.
Answer:
Metal hydroxide (or metal oxide when the metal reacts with steam). Example: 2Na + 2H₂O → 2NaOH + H₂.
In simple words: Metal + water gives a hydroxide or an oxide, plus hydrogen.

Teacher's Note:
1. With steam the product is a metal oxide.
2. Not every metal reacts with water.

Question 7. The chemical formula of calcium nitride is _________.
Answer:
Ca₃N₂. Calcium forms Ca²⁺ and nitrogen forms N³⁻; criss-crossing the charges gives Ca₃N₂.
In simple words: Three Ca²⁺ ions balance two N³⁻ ions.

Teacher's Note:
1. Use the criss-cross method of valencies.
2. Check that total positive charge (6) equals total negative charge (6).

Question 8. Cinnabar is an ore of _________ .
Answer:
Mercury. Cinnabar is mercury(II) sulphide, HgS.
In simple words: Cinnabar (HgS) gives mercury.

Teacher's Note:
1. Heating cinnabar in air gives HgO, which then decomposes to mercury.
2. Learn the ore names with their formulae.

Question 9. When Cu is kept in open air, it slowly loses its shining brown surface and acquire a green colour coating. It is due to the formation of _________ .
Answer:
Basic copper carbonate, CuCO₃·Cu(OH)₂, formed by the action of moist carbon dioxide and oxygen of the air on copper.
In simple words: The green coat on copper is basic copper carbonate.

Teacher's Note:
1. This slow change is called corrosion.
2. Silver, in contrast, turns black.

Question 10. During electrolytic refining of zinc, Zn will get deposited on _________ .
Answer:
The cathode. Pure zinc is deposited on the cathode while the impure zinc anode dissolves.
In simple words: Metal is always deposited at the cathode.

Teacher's Note:
1. Anode: impure metal. Cathode: thin strip of pure metal.
2. The electrolyte is a soluble salt of the same metal.

Very Short Answer Questions

Question 11. Name two metals which are found in nature in the native state.
Answer:
Gold and platinum (silver and copper are also found free to some extent).
In simple words: Unreactive metals occur free in nature.

Teacher's Note:
1. The less reactive the metal, the more likely it occurs free.
2. Gold and platinum lie at the bottom of the series.

Question 12. Name the property due to which metal produces sound when metal is struck with hammer.
Answer:
Sonority (metals are sonorous). This is why bells are made of metals.
In simple words: Metals ring when they are struck.

Teacher's Note:
1. Do not confuse sonority with malleability.
2. Non-metals are non-sonorous.

Question 13. Name the two metals from the following that will melt at body temperature (37°C)? Gallium, Magnesium, Caesium, Aluminium.
Answer:
Gallium and caesium have very low melting points (about 30 °C and 28.5 °C), so they melt at body temperature. Magnesium and aluminium have high melting points.
In simple words: Gallium and caesium melt in the hand.

Teacher's Note:
1. Check the melting points before choosing.
2. Most metals melt only at high temperatures.

Question 14. An element forms an oxide, A₂O₃ that has acidic nature. Identify A as a metal or non-metal.
Answer:
A is a non-metal, because non-metals form acidic oxides. Metal oxides are generally basic.
In simple words: An acidic oxide means the element is a non-metal.

Teacher's Note:
1. Amphoteric metal oxides such as Al₂O₃ show both natures.
2. Test the oxide solution with litmus.

Question 15. Name any one metal that will neither reacts with cold water nor with hot water, but it will reacts with heated steam to liberate hydrogen gas.
Answer:
Aluminium (zinc and iron also behave in this way): 2Al + 3H₂O(g) → Al₂O₃ + 3H₂.
In simple words: Aluminium reacts only with steam.

Teacher's Note:
1. The products with steam are a metal oxide and hydrogen.
2. Magnesium reacts with hot water.

Question 16. Name any one metal that will react with a very dilute HNO₃ to liberate hydrogen gas.
Answer:
Magnesium (manganese also does): Mg + 2HNO₃ → Mg(NO₃)₂ + H₂.
In simple words: Mg and Mn are the exceptions with nitric acid.

Teacher's Note:
1. Other metals give oxides of nitrogen, not hydrogen.
2. The acid must be very dilute.

Question 17. Why do we use copper and aluminium wire for transmission of electric current?
Answer:
Copper and aluminium are good conductors of electricity and are ductile, so they can be drawn into thin wires. Aluminium is also light and cheap.
In simple words: They carry current well and can be drawn into wires.

Teacher's Note:
1. Give both conductivity and ductility.
2. Silver is a better conductor but too costly.

Question 18. In the formation of the compound XY, atoms of X lost one electron each, while atoms of Y gained one electron each. What is the nature of the bond in XY?
Answer:
Transfer of electrons from X to Y forms X⁺ and Y⁻ ions held by electrostatic attraction. The bond is an ionic (electrovalent) bond.
In simple words: Giving and taking of electrons makes an ionic bond.

Teacher's Note:
1. X is a metal and Y is a non-metal.
2. Sharing of electrons would give a covalent bond.

Question 19. What is a thermite reaction?
Answer:
The reaction of a metal oxide with aluminium, which is highly exothermic and gives the metal in the molten state, is the thermite reaction. Example: Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat. It is used to join railway tracks and cracked machine parts.
In simple words: Aluminium melts iron out of its oxide and the molten iron is used for welding.

Teacher's Note:
1. It is a displacement as well as a redox reaction.
2. Write the balanced equation as proof.

Question 20. Why do we apply paint on iron articles?
Answer:
Paint forms a coating that keeps air and moisture away from the iron surface, so the iron does not rust.
In simple words: Paint blocks air and water from reaching the iron.

Teacher's Note:
1. Oiling, greasing and galvanising work in the same way.
2. Rusting needs both air and moisture.