1. (d) AgNO3 solution and copper

2. (c) Applying coating of zinc

3. (a) Calcium

4. (c) Zinc is more reactive than tin

5. (a)Place the sample on an iron block. Strike with hammer. If the sample takes the
 shape of a sheet, it is a metal. If it breaks into pieces, it is a non-metal.
 Set up the arrangement by using a bulb, a battery, wires and switch. Insert the
 samples of metals and non-metals in the clips one by one and turn the switch on. If
 the bulb glows, the sample is a metal, if not, then the sample is non-metal.

 (b)The above two methods can, in general, be used to distinguish between metals
 and non-metals.

6. Metal oxides which show both acidic as well as basic behavior are called amphoteric
 oxides. Such metal oxides react with both acids and bases.
 Example: Aluminum oxide, zinc oxide

7. Magnesium and zinc metals displace hydrogen from dilute acids. Copper and silver
 do not displace hydrogen from dilute acids.

8. Impure metal M is made the anode, thin strips of pure metal M as cathode and a salt
 solution of metal M as electrolyte.

9. (a) Sulphur is a non-metal. Oxides of non-metals are acidic. In this case sulphur
 dioxide is produced which is acidic.
 (i) No action of the gas
 (ii) wet litmus paper will turn red.
 (b) S(s) +O2 (g) SO2 (g)

10. Rusting of iron can be prevented by
 (i) By applying grease or paint.
 (ii) By galvanizing

11. Acidic oxides are formed when non-metals combine with oxygen.

12. (a) These metals are un-reactive. They do not react with oxygen and other gases
 present in air and with moisture. Thus, their shine is maintained. That is why these
 metals are used to make jewellery.
 (b) Reaction of sodium, potassium and lithium with oxygen is so violent that they
 catch fire. To prevent accidental fire, they are stored under kerosene oil.
 (c) This is because aluminum is a good conductor of heat. Aluminum forms a layer of
 aluminum oxide at high temperature which is prevent the further corrosion.
 (d) It is easier to reduce oxide than the carbonates and sulphide to the metals.

13. Copper, on keeping in air reacts with atmospheric carbon dioxide to form a green
 layer of copper carbonate. Copper carbonate reacts with citric acid present in lemon
 or tartaric acid present in tamarind to form soluble copper citrate or copper
 tartarate. The vessels are thus cleaned using water.

14. Metals and non-metals can be differentiated on the basis of following chemical


Metals Non-metals
1. Metals displace hydrogen from water.
2. Metals are basic oxide.
3. Metals displace hydrogen from dilute
4. Metals form ionic chlorides with

1. Non-metal do not displace hydrogen
from water.
2. Non-metals are acidic oxides.
3. Non-metals displace hydrogen from
Dilute acids.
4. Non-metals form covalent chlorides
with chlorine.

15. Aqua regia, which is a mixture of 3 parts concentrated HCl and part of concentrated
 nitric acid dissolves gold. The man put the gold bangles in this solution. The outer
 dirty layer of gold bangles dissolved in aqua regia bring out the shining bangles.
 As the outer layer of bangles dissolved in aqua regia, the weight was reduced
16. Electrical conductivity of a metal is decreased when it is alloyed with another metal
 or non-metal. Thus, the electrical conductivity of steel is much less than that of pure .

 That is why copper is used to make hot water tanks and not steel. 

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