Question

0.7 g of Na₂CO₃ · x H₂O is dissolved in 100 mL water, 20 mL of which required 19.8 mL of  0.1 N HCl. The value of x is :

(a) 4

(b) 3

(c) 2

(d) 1

Answer 1

Correct option is (c) 2

Answer 2

Correct option is (c) 2

 \(N_1V_1=N_2V_2\)

\(N_1\times20mL=0.1\times19.8mL\)

\(N_1=0.099N\)

\(\therefore\) \(0.099N=\frac{0.7\times2\times1000}{(106+x18)\times100}\)

\(106+x18=\frac{14}{0.099}\)

\(106+x18=141.4\)

\(x18=35.4\)

\(x\approx2.\)