Materials: Metals And Non-metals

Option (a) is correct.

Zinc is a metal and the rest are non-metals. Due to the property of malleability of metals, metals can be beaten into sheets and not non-metals. Thus, Zince can be beaten into sheets.

Option (c) is correct

Generally, metals are ductile because they can be drawn into wires.

(a) Phosphorus is a very reactive non-metal.

(b) Metals are good conductors of heat and electricity.

(c) Iron is more reactive than copper.

(d) Metals react to acids to produce hydrogen gas.

(a) False. Metals also react with acids.

(b) True. Because it is an alkali metal.

(c) False. Because zinc is more reactive than copper.

(d) False. Because Coal is not a metal.

(a) Aluminium foils are used to wrap food items because aluminium metal is malleable. Therefore, it can be beaten into thin sheets called foils.

(b) Metals are good conductors of heat and electricity. Therefore, immersion rods for heating liquids are made of metallic substances, so that they can conduct heat and electricity.

(c) A metal can displace a less reactive metal from its salt in an aqueous solution. Because zinc is more reactive than copper. Therefore, copper cannot displace zinc from its salt solution (as shown in equation 1). But, Zinc can displace copper form its salt solution.

^{Cu(s)+ ZnSO}₄^{(aq)→No reaction …………… (1)}

^{Zn(s)+ CuSO}₄^(aq)→ZnSO₄ ……………… (2)

(d) Sodium and potassium are stored in kerosene because they are highly reactive elements. They can easily catch fire even when in contact with air.

Lemon pickle cannot be stored in aluminium utensils because lemon pickle contains acids, which can react with aluminium. Because aluminium is a metal and metals react with acids to liberate hydrogen gas. This can lead to the spoiling of the pickle.

(a) When dilute sulphuric acid is poured on a copper plate, bubbles of hydrogen gas appear on the surface of plate.
This happens because The copper being a reducing agent reacts with sulphuric acid to produce hydrogen gas. This can be shown by following equation:

This can be shown by the following equation:

H₂SO₄ (l) + Cu (m) → CuSO₄ (l) + H₂ (g)↑
sulphuric acid Copper Copper sulphate Hydrogen gas

(b)When we add iron in the copper sulphate solution. The blue colour of copper sulphate fades and there is deposition of copper on the iron nail.
Iron being more reactive displaces copper from copper sulphate solution.

This can be shown by the following equation:

Fe(s) + CuSO₄ (l) → FeSO₄(l) + Cu(m)
Iron Copper sulphate Ferrous sulphate Copper

After Saloni has collected the gas evolved in the test tube.

(a) Add a few drops of water in the test tube containing gas. Now, cover the test tube and shake it well. After shaking, test the solution with blue litmus and red litmus. It will turn blue litmus red. Thus, the gas is acidic in nature. If it would not have changed the colour of litmus that means gas was basic.

(b) Charcoal reacts with oxygen to form carbon dioxide gas.

C (Carbon from Charcoal) ⁺ O₂ (Oxygen) ^→ CO₂ (Carbon Dioxide)

Carbon dioxide reacts with water to form carbonic acid, which turns blue litmus paper red.

CO₂ (Carbon Dioxide) ⁺ H₂O (Water) ^→ H₂CO₃ (Carbonic Acid)

To polish a gold ornament, it is dipped in a liquid called aqua regia (a mixture of hydrochloricacid and nitric acid in ratio 3:1).

The gold layer starts dissolving when put in aqua regia which causes reduction in the weight of gold amount. The outer layer of gold dissolves and the inner shiny layer appears.