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How many water molecules of crystallisation are present in one molecule of washing soda?
AEight
BFive
CTen
DSeven
Answer & Solution
Correct answer: C. Ten
1. Washing soda is hydrated sodium carbonate.
2. Its formula is Na2CO3 . 10H2O.
3. Therefore it contains 10 water molecules of crystallisation.
_Source: RRB Group D CEN-02/2018 PYQ, Q.17._