Question

If the water of crystallisation in gypsum is X and Y in washing soda then the value of X + Y is ________

• A. 8
• B. 10
• C. 12
• D. 14

Answer 1

The correct option is C 12

• Gypsum $\left(CaS{O}_4.2H_{2}O\right)$ contains two molecules of water of crystallization.

So X= 2

• Sodium carbonate crystal or washing soda $\left(N{a}_{2}C{O}_3.10H_{2}O\right)$ contains ten molecules of water of crystallization.

So Y =10
So, X + Y = 2 + 10 = 12