Q: The hydrated salt Na_{2}SO_{4}. x H_{2}O undergoes 55% loss in weight on heating and becomes anhydrous. The value of x will be

(A) 5

(B) 3

(C) 7

(D) 10

Sol: Percent loss of H_{2}O in one mole of Na_{2}SO_{4}. x H_{2}O

$\large = \frac{18 x \times 100}{140 + 18x} = 55$

x = 10

Ans: (D)