set 3 MCQ Questions & Answers Detailed Explanation

Question : 1

The chemical formula of plaster of paris is

a) $(CaSO_4).2H_2$O

b) $CaSO_4.5H_2$O

c) 2CaS$O_4.H_2$O

d) COSO₄. MGO

Question : 2

Purity of a solid substance can be checked by its

a) solubility in water

b) melting point

c) boiling point

d) solubility in alcohol

Question : 3

The chemical formula of Borax is

a) BaS$O_4$

b) $Na_2B_4O_7$

c) CaOC$l_2$

d) Ca$(SO_4)_2$

Question : 4

Iron sheet kept in moist air covered with rust. Rust is

a) a mixture of iron and dust

b) an element

c) a compound

d) a mixture of iron, oxygen and water

Question : 5

The size of colloidal particles usually lies in the range

a) 10^–3 - 10^–5 cm

b) 10^–7 - 10^–9 cm

c) 10^–5 - 10^–7 cm

d) 10^–2 - 10^–6 cm