The number of molecules are the same in which of the following pairs?
|A|| 32 grams of O2 and 32 grams of SO2|
|B|| 49 grams of NO2 and 40 grams of NaOH|
|C|| 20 grams of HF and 36 grams of H2O|
|D|| 60 grams of C2H6 and 156 grams of C6H6|
Ans. D The question tests your understanding of the concept of mole. In Choice A, we have 32 g of O2 which corresponds to 1 mol of oxygen, and 32 g of SO2 which corresponds to half a mol. Choice A is not correct. In Choice B, we have 49 g of NO2 which corresponds to a little more than 1 mol, and 40 g of NaOH which corresponds to 1 mol. So this may be our answer. Choice C is not correct, because we have 20 g of HF which is 1 mol, and 36 g of water which is 2 moles. So Choice C is incorrect. Choice D has 60 g of C2H6 which is 2 moles, and 156 g of C6H6 is also 2 moles. So D is a better choice than B.