A compound possesses 8% sulphur by mass. The least possible molecular mass of the compound is:
Correct answer: C. 400.
- A. 200.
- B. 155.
- C. 400.
- D. 355.
Explanation
For the least possible molecular mass of the compound there must be only 1 sulphur atom in the compound. We know that the molar mass of a sulphur atom is 32g/mol. Thus, we should find the mass of the compound which will have exactly 32g of sulphur in its molecular mass. It is given that the compound contains 8% sulphur by mass. What this means is that in 100g of the compound, we will have 8g of sulphur. Now all we have to do is find the mass of the compound which will have 32g of sulphur. Let us denote the overall mass of the compound as x: Sulphur : Compound 8 : 100 32 : x = (100 x 32)/8 = 400 g Hence, the minimum molecular mass of the compound which will contain 8% sulphur by mass is 400g.
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