Chapter 3: Metals and Non-metals

Solution: Option d i.e., AgNO₃ solution and copper is the correct answer. Copper displaces the silver cations (reducing them to the elemental metal), in the process copper itself is being oxidised to Copper II cations (Cu²⁺) and going into solution. So silver metal is seen precipitating out and a copper II nitrate solution will remain.

Cu(s) + 2AgNO₃ (aq) → Cu(NO₃)₂ (aq) + 2Ag (s)

Solution: Answer is (c) Applying a coat of zinc

Though applying grease and applying paint do prevent iron from rusting, we cannot apply these methods on a frying pan. Hence, applying a coat of zinc is the most appropriate method to prevent an iron pan from rusting.

Solution: Correct answer is option (a) Calcium.

Calcium reacts with oxygen to give calcium oxide. Calcium oxide is soluble in water to give Calcium Hydroxide.

Carbon forms carbon-oxide with oxygen which is gas, hence option B is wrong

Silicon reacts with oxygen and forms silicon dioxide. This is insoluble in water. So option C is not correct.

Iron reacts with oxygen and forms Iron dioxide. This is insoluble in water. So option D is not correct.

Solution: Answer is c. Food cans are coated with tin and not with zinc because zinc is more reactive, that is electro positive than tin.

1. Metals are malleable and can be easily drown into sheets by hitting with hammer. On the other hand, if we beat non-metals they break down and they cannot be drawn into sheets as they are non-malleable. Metals are good conductors of electricity, hence they make bulb when you connect metals with a battery, wire and bulb. Similarly, if non-metals are bad conductors of electricity, they fail to light up the bulb on connecting with wire and battery.
2. These experiments can be helpful to demonstrate the malleability and electric conductivity of the metals and non-metals

Solution: Oxides that react with both acids and bases to form salt and water are known as amphoteric oxides. Examples:  PbO and Al₂O₃.

Amphoteric oxides are the one which react with both acids and bases to form salt and water. Examples:  Lead oxide – PbO and Aluminium oxide – Al₂O₃.

Solution: Zinc (Zn) and Magnesium (Mg) are the two metals which will displace hydrogen from dilute acids as they are very reactive metals. Gold (Au) and Silver (Ag) are the metals which will not replace hydrogen from dilute acids as these metals are less reactive.

Solution: In the process of electrolytic refining of metal called ‘M’, an impure and thick block of metal M is considered an anode, a thin strip or wire of pure metal M is taken as cathode. A suitable salt solution of metal M is considered as the electrolyte.

Solution: a) When sulphur powder is burnt in the air sulphur-di-oxide is formed.

(i) Sulphur-di-oxide does not have any effect on dry litmus paper.

(ii) Sulphur-di-oxide turn the moist litmus paper from blue to red as contact of SO₂ with water turns to sulfurous acid.

(b) S(s) + O₂(g) → SO₂(g)

SO₂(g) + H₂O →H₂SO₃

1. Iron can be prevented from rusting by coating the surface of the iron with rust proof paints
2. By applying oil/grease on the surface of iron objects as it will prevent the iron surface to get in contact with air consisting of moisture.