JEE Chemistry 2023 Question with Solution

Given: Volume of $O_2$ is $2.8375 \, \text{L}$ at STP.

Find: Number of molecules and moles.

At STP, one mole of a gas occupies

So, the number of moles of $O_2$ is

Now use Avogadro's number:

Therefore, number of molecules is

Therefore, the number of molecules and moles are $7.527 \times 10^{22}$ and $0.125 \, \text{mol}$ respectively. The correct option is A.

Given: Volume of $O_2$ is $2.8375 \, \text{L}$ at STP.

Find: Number of moles and number of molecules.

One part of the solution mentions $22.7 \, \text{L}$ at STP, while another part uses $22.4 \, \text{L}$. The final numerical answer shown matches the $22.4 \, \text{L}$ calculation used in the image and in Approach Solution 2.

Using

and then

we obtain the listed answer.

Hence, the defensible final answer from the solution is Option A.