A40.15 gram sample of a hydrate of na2so4 was heated thoroughly in a porcelain crucible, until its weight remained constant. after heating, 21.27 grams of the anhydrous compound remained. what is the formula of the hydrate?

The formula of the hydrate of the sodium sulfate is :

Explanation:

Mass of hydrated sodium sulfate = 40.15 gram

Mass of completely dehydrated sodium sulfate = 21.27 gram

Mass of water molecules present in hydrated sodium sulfate =x

40.15 gram =  21.27 gram + x (Law of conservation of mass)

x  = 40.15 gram - 21.27 gram = 18.88 g

Moles of water =

Moles of sodium sulfate =

Whole number ratio of sodium sulfate and water:

Sodium sulfate =

Water =

The formula of hydrate be

So, the formula of the hydrate of the sodium sulfate is :

the answer your looking for is c).