Question

A compound processes 8% sulphur by mass.
The least molecular mass is:

• A. 200
• B. 400
• C. 155
• D. 355

Answer 1

Answer: (B)

400

The compound having the least molecular mass should contain the minimum amount of Sulphur or simply 1 atom of sulphur

Let the molecular mass of the compound(in amu) be $x$

Mass of sulphur in the compond =8 percent of the total molecular mass of $x$=$\frac{8x}{100}$

Since the molecular mass of one mole of sulphur is 32, the compound must contain this amount of sulphur

Hence $\frac{8x}{100}=32$

which gives $x=400$