The mass of 0.5 mole of N₂ gas is

The mass of 0.5 mole of N₂ gas is

7 g
14 g
21 g
28 g
This question was previously asked in
UPSC NDA-2 – 2024
The correct answer is B) 14 g.
The mass of a substance can be calculated using the number of moles and its molar mass. The formula is: Mass = Number of moles × Molar mass.
Nitrogen gas is diatomic, represented as N₂. The atomic mass of Nitrogen (N) is approximately 14 g/mol. Therefore, the molar mass of N₂ gas is 2 × 14 g/mol = 28 g/mol.
Given the number of moles is 0.5 mole, the mass of 0.5 mole of N₂ gas is 0.5 mol × 28 g/mol = 14 g.
A mole is a unit of amount of substance, defined as containing Avogadro’s number (approximately 6.022 × 10²³) of elementary entities (atoms, molecules, ions, etc.). The molar mass of a substance is the mass of one mole of that substance.