Question

no. of atoms in 16g of methane

Answer 1

molecular formula of methane = CH4 
we know, 
atomic mass of C = 12 g/mol 
atomic mass of H = 1 g/mol 
so, 
molecular mass of CH4 =( 12 + 4 × 1 ) g/mol = 16 g/mol 

also we know, 
no of molecule = {given weight /molecular weight } × 6.023 × 10²³ 

here, 
given weight = 16 g
molecular weight = 16 g/mol 

so, 
no of molecules = ( 16/16) × 6.023 × 10²³ 
= 6.023 × 10²³

Answer 2

No of molecules = wt/gmw *avagadro no
6.023*10^23