Given:
Number of molecules of hydrogen chloride (HCl) = 6.02 ×
1025 We have to find the number of gram molecules of chlorine in 6.2 ×
1025 molecules of hydrogen chloride .
1 gram molecule of any molecule contains = 6.023 ×
1023 (Avogadro's constant) molecules
Thus,
1 gram molecule of HCl contains = 6.023 ×
1023 (Avogadro's constant) molecules of HCl
Now, one molecule of HCl contains = One molecule of chlorine 6.023 ×
1023 molecules of HCl contains = 6.023 x
1023 molecules of Chlorine
Or,
One gram molecule of HCl contains = 6.023 x
1023 molecules of Chlorine
The number of gram molecules of chlorine in 6.02 x
1025 hydrogen chloride molecules
=
= 100
Hence, option 'B' is correct.