Question 1

One mole is defined as the amount of substance that contains?

Accepted Answer

6.022 × 10^23 elementary entities. Option D is correct because one mole contains Avogadro’s number of entities. These entities can be atoms, molecules, ions, or electrons. Avogadro’s constant is about 6.022 × 10^23 per mole.

Question 2

The value of Avogadro’s constant is approximately?

Accepted Answer

6.022 × 10^23 mol^-1. Option B is correct because Avogadro’s constant is about 6.022 × 10^23 mol^-1. It tells how many particles are in 1 mole. It links microscopic particles with macroscopic amount.

Question 3

At STP, the molar volume of an ideal gas is closest to?

Accepted Answer

22.4 L. Option D is correct because 1 mole of an ideal gas occupies about 22.4 L at STP. This value is used to convert between moles and gas volume at STP. Half a mole at STP occupies about 11.2 L.

Question 4

The molar mass of carbon dioxide (CO2) is?

Accepted Answer

44 g/mol. Option D is correct because CO2 has molar mass 12 + 16 + 16 = 44 g/mol. Molar mass is the mass of 1 mole of a substance. It is numerically equal to molecular mass in grams.

Question 5

How many moles of water (H2O) are present in 9 g of water? (H=1, O=16)?

Accepted Answer

0.50 mol. Option B is correct because moles = mass/molar mass = 9/18 = 0.50 mol. The molar mass of water is 18 g/mol. Moles help convert mass into number of molecules.

Mole Concept — Set 1