Exams › JEE Main › Chemistry

If the relative atomic mass unit were defined as $\frac{1}{6}$ of the mass of a carbon atom instead of $\frac{1}{12}$, then the mass of one mole of a substance would

1. depend on the molecular mass of the substance
2. stay the same
3. become twice as large
4. be reduced to half

Correct answer: become twice as large

Solution

The new atomic mass unit would be twice the old one because $\frac{1}{6}$ of a carbon atom is double $\frac{1}{12}$ of a carbon atom. Therefore, numerical atomic/molecular masses in that unit become half, so the mass of one mole expressed in grams becomes twice as large.

Related JEE Main Chemistry questions

• A 100 mL sample of a urea solution contains $6.02 \times 10^{20}$ molecules of urea. What is the molarity of the solution? (Take Avogadro constant, $N_A = 6.02 \times 10^{23}\ \text{mol}^{-1}$.)
• When 4.9 g of $\mathrm{H_2SO_4}$ reacts with NaCl, the products formed are 6 g of sodium hydrogen sulphate and 1.825 g of HCl. What mass of NaCl was decomposed?
• Which of the following has the least mass?
• What amount of magnesium phosphate, $\mathrm{Mg_3(PO_4)_2}$, in moles is needed to provide 0.25 mole of oxygen atoms?
• Haemoglobin has 0.33% iron by mass. If its molecular mass is about 67200 and the atomic mass of iron is 56, how many iron atoms are present in a single haemoglobin molecule?
• For the reaction 2Al(s) + 6HCl(aq) → 2Al^{3+}(aq) + 6Cl^{-}(aq) + 3H_{2}(g), which statement is correct?

⚔️ Practice JEE Main Chemistry free + battle 1v1 →