Question

Calculate the number of moles present in 120 g of Mg. (AMU of Mg is 24)
1. 2
2. 5
3. 4
4. 3
5.

Answer 1

Correct Answer - Option 2 : 5

Concept:
Avogadro's number: The number of units present in one mole of a given substance is called the Avogadro's number.

• Avogadro's number (NA) is equal to 6.022140857 × 1023.
• Avogadro's number is the no of atoms, elements or molecules present in 1 mole.
• Mass of 1 mole of substance = Atomic mass of individual

Calculation:

• Atomic mass of Mg atom = 24
• Mass of 1 mole of Mg atom = atomic mass of Mg atom = 24

24 g of Mg atom contain mole = 1

1 g of Mg atom will contain mole = 1 / 24

Thus 120 g of Mg will be contain mole = 1 / 24 × 120

⇒ 5