Question

The number of molecules in 16 g of oxygen gas is _______. 

(A) 6.022 x 10²³ 

(B) 3.011 x 10²³ 

(C) 3.011 x 10²² 

(D) 1.5 x 10²³

Answer 1

Correct option: (B) 3.011 x 10²³ 

Number of molecules = n x 6.022 x 10²³

Now, n = \(\cfrac{mass\, of\, oxygen}{molar\, mass\, of\, oxygen}\) = \(\frac{16}{32}\) = 0.5

∴ Number of molecules = 0.5 x 6.022 x 10²³

= 3.011 x 10²³