Limestone is calcined to give a white solid A. A reacts with water to form B, a sparingly soluble base. B absorbs chlorine to form bleaching powder, CaOCl2 (relative formula mass 127). The mass of bleaching powder obtained from 28.0 g of A, assuming complete conversion at each step, is

JEE Advanced levelSingle correct optionDifficulty 3 of 3sb200

Limestone is calcined to give a white solid A. A reacts with water to form B, a sparingly soluble base. B absorbs chlorine to form bleaching powder, $CaOCl X_{2}$ (relative formula mass 127). The mass of bleaching powder obtained from 28.0 g of A, assuming complete conversion at each step, is

A is

CaO

(56 g/mol) and B is

Ca (OH) X_{2}

. The steps are

CaO + H X_{2} O Ca (OH) X_{2}

and

Ca (OH) X_{2} + Cl X_{2} CaOCl X_{2} + H X_{2} O

, each 1 : 1. Moles of A

= 28.0/56 = 0.500

so the mass is

0.500 \times 127 = 63.5