Question

Fill in the blanks.

(a) Gold of 100% purity is ………… carat gold.

(b) Bronze contains the metals ………… and ………… .

(c) The ………… gas is released when metals react chemically with acids.

(d) Oxides of metals have ………… properties.

(e) The non-metal ………… is used in gun powder.

Answer 1

(a) Gold of 100% purity is 24 carat gold.

• 24 Carat gold is the purest form of gold because it is free from any impurities like other metals or oxides.
• 24 Carat gold is used in the making of jewllery.

(b) Bronze contains the metals copper, zinc, and tin.

• Bronze is an alloy of copper, zinc, and tin.
• The bronze alloy contains $80$% copper, $10$% zinc, and $10$% tin.
• Bronze is used in the making of household utensils.

(c) The hydrogen gas is released when metals react chemically with acids.

• When a metal placed above hydrogen in reactivity series reacts with an acid, it displaces the hydrogen from the acid and leads to the evolution of hydrogen.
• Such metals are known as active metals.​
• Example: Zinc$\left(Zn\right)$ reacts with hydrochloric acid$\left(HCl\right)$ leading to the formation of zinc chloride$\left(ZnC{l}_2\right)$ and hydrogen gas$\left(H_2\right)$.

$Zn\left(s\right)+2HCl\left(aq\right)⟶ZnC{l}_2\left(s\right)+H_2\left(g\right)$

(d) Oxides of metals have basic properties.

• Oxides of metal are basic in nature because they react with an acid to form salt and water.​
• Example: Copper oxide reacts with hydrochloric acid to form salt copper chloride and water.

$2HCl+CuO⟶CuC{l}_2+H_{2}O$

(e) The non-metal sulphur is used in gun powder.