Question

Which of the following formulae is not correctly depicted?

• A. Molar mass $=\frac{\text{Mass of substance}}{\text{Moles of substance}}$
• B. Mass of one molecule of a substance $=\frac{\text{Gram molecular mass of the substance}}{\text{Avogadro’s number }}$
• C. Number of molecules $\frac{\text{Mass of the substance }}{\text{Molar mass }}\times$ Avogadro's no.
• D. Number of moles $\times$ Molar mass = Number of molecules

Answer 1

Answer: (D)

Molar mass $=$ mass per mole of the substance $=\frac{\text{ Mass of substance }}{\text{ Moles of substance }}$
Rewriting it as: Number of moles of a substance $=\frac{\text{ Mass of substance }}{\text{ Molar mass }}$
Also, number of moles of a substance $\times$ Molar mass $=$ mass of the substance.
Number of molecules $=$ Number of moles $\times$ Avogadro's constant $=$
$\frac{\text{ Mass of substance }}{\text{ Molar mass }}\times$ Avogadro/s no.