Answer:
0.03 mol
Step-by-step explanation:
The equation relating the number of moles and number of atoms is:
Number of atoms = number of moles × 6.02 × 10²³
[6.02 × 10²³ is the Avogadro's constant and is the number of particles in 1 mole of any substance.]
By rearranging the equation, we can find the number of moles of calcium.
Number of moles = (3.01 × 10²²) ÷ (6.02 × 10²³)
Number of moles = 0.05 moles of calcium
Now the only data we know about these two elements are their Mr values, so we are going to find the number of moles of magnesium using ratio.
Moles : Mr
0.05 mol : 40.1
x : 24.3
[we are going to assume that x is the number of moles of magnesium that we have to find out.]
Cross multiply the ratios.
40.1x = 0.05 × 24.3
x = 1.215 ÷ 40.1 = 0.03 mol