Question

the number of oxygen atoms on 1 mole of plaster of paris are
a) 4NA
b) 3NA
c)3.5NA
d) 4.5NA

Answer 1

the correct answer is (a)4NA

Answer 2

Answer: The correct answer is Option d.

Explanation:

The chemical formula for plaster of Paris is $CaSO_4.\frac{1}{2}H_2O$

In 1 mole of Plaster of Paris, 1 mole of calcium atoms, 1 mole of sulfur atom and 4.5 moles of oxygen atoms are present.

According to mole concept:

1 mole of a compound contains $6.022\times 10^{23}$ number of particles.

The number $6.022\times 10^{23}$ is known as Avogadro's number and is written as $N_A$

So, 1 mole of Plaster of Paris will contain $(4.5\times N_A)=4.5N_A$ number of oxygen atoms.

Hence, the correct answer is Option d.