JEE Main · 2019 · 10 Apr 2019 · Shift 2 · s-Block Elements

A hydrated solid X on heating initially gives a monohydrated compound Y . Y upon heating above 373 K leads to an anhydrous white powder

Z . X

and Z , respectively, are:

Answer: (A)

Solution

The clue is the stepwise loss of water. Washing soda,

Na X_{2} CO X_{3} \cdot 10 H X_{2} O

, first drops most of its water on gentle heating to leave the monohydrate

Na X_{2} CO X_{3} \cdot H X_{2} O

, which is

Y

. Pushed above

373 K

this last water goes too, leaving anhydrous sodium carbonate, soda ash. So

X

is washing soda and

Z

is soda ash.

JEE Main · 2019 · 10 Apr 2019 · Shift 2 · Single correct option