Question

A compound contains 1.6% sulphur by mass in its molecule. Correct option(s) about the compound is/are:

• A. If one mole of compound contains 64 g of sulphur then molar mass of compound is 4000 g/mol
• B. If one molecule of compound contains only one sulphur atom then vapour density of compound is 2000
• C. If vapour density of compound is 3000 then one molecule contains 3 sulphur atoms
• D. If molar mass of compound is 2000 g/mol then one gram molecule contains one atom of sulphur

Answer 1

Answer: (A), (C), (D)

If molar mass of compound is 2000 g/mol then one gram molecule contains one atom of sulphur

Given, molar mas of sulphur = 32 g/mol and % of S = 1.6% by mass
(a) Molar mass of molecule =$\frac{100}{1.6}\times 64=4000$ if one molecule contains two S atoms
(b) Molar mass of molecule = $\frac{100}{1.6}\times 32=2000$ if one molecule contains one S atom
So, vapour density $=\frac{1}{2}\times molarmass$
$=\frac{1}{2}\times 2000=1000$
(c) Molar mass of molecule =$\frac{100}{1.6}\times 96=6000$ if one molecule contains 3 S atoms, vapour density = 3000
(d) Molar mass of molecule = 2000
$\Rightarrow \frac{100}{1.6}\times m=2000\Rightarrow m=32$
$\therefore$ One molecule contains one sulphur atom.