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Q.
Anhydrous $ Na_{2}CO_{3} $ is also known as :
AFMCAFMC 2001
Solution:
Anhydrous $Na _{2} CO _{3}$ is called soda ash
$\underset{\text{Washing soda}}{Na_2CO_3 \cdot 10H_2O} \xrightarrow[\text{(efflorescence)}]{\text{in air}} Na_2CO_3 \cdot H_2O + 9H_2O$
$Na _{2} CO _{3} \cdot 10 H _{2} O \xrightarrow{\Delta}\underset{\text { soda ash }}{ Na _{2} CO _{3}}+10 H _{2} O$