Question

The weight of 1 x 10²² molecules of CuSO₄.5H₂O is _______.

(A) 41.59 g 

(B) 415.9 g 

(C) 4.159 g 

(D) none of these

Answer 1

Correct option: (C) 4.159 g

Molecular mass of CuSO₄.5H₂O

= Cu + 32 + (9 x O) + (10 x H)

= 63.5 + 32 + (9 x 16) + (10 x 1)

= 249.5 g

6.023 x 10²³ molecules of CuSO₄.5H₂O weighs 249.5 g

∴ 1 x 10²² molecules of CuSO₄.5H₂O

will weigh \(\cfrac{249.5\, \times1\, \times 10^{22}}{6.023\, \times 10^{23}}\) = 4.159 g