Choose the correct option:


(i) The chemical formula of baking soda is:


(a) NaHSO4 (b) Na2CO3

(c) NaHCO3 (d) Na2CO3
.10H2O


(ii) The chemical substance that is used for disinfecting drinking water to make it free of

germs is:


(a) CaCl2 (b) CaOCl2

(c) FeCl3 (d) MgCl2


(iii) Glass is a


(a) Liquid (b) Solid

(c) Transparent carbon polymer (d) Super-cooled liquid


(iv) Plaster of Paris hardens by


(a) Losing CaCl2 (b) Releasing CO2

(c) Absorbing water (d) Releasing water