Question

Assertion: One mole of oxygen and one mole of $S{O_2}$contains the same number of oxygen atoms.
Reason: the amount of oxygen in one mole of ${O_2}$ is the same as that in one mole of $S{O_2}$
A.Both assertion and reason are correct and reason is the correct explanation for assertion
B.Both assertion and reason are correct and reason is not the correct explanation for assertion
C.Assertion is correct but reason is incorrect
D.Both assertion and reason are incorrect

Answer 1

To solve this question, we need to first understand about the formation of oxygen molecules. Then we can equate the number of oxygen atoms in both the molecules. After that, using the mole concept, we can establish a relation between the assertion and the reason.

Complete Step-by-Step Answer:
Before we move forward with the solution of the given question, let us first understand some important basic concepts.
There are 2 atoms present in an oxygen molecule. On the other hand, in sulphur dioxide or $S{O_2}$, we can see that there is one atom of sulphur and 2 atoms of oxygen present. Hence, we can say that the number of atoms in the mole of oxygen and one mole of $S{O_2}$ is the same. Hence, the assertion is correct.
Now, let us understand a concept known as mole theory. According to mole theory, one mole of any element or compound would contain an equal number of the atoms or molecules. Hence, if the number of moles of oxygen in the oxygen molecule is equal to the number of moles of oxygen in the $S{O_2}$ molecule, then the number of oxygen atoms present in the oxygen molecule would be equal to the number of oxygen atoms in the $S{O_2}$ molecule. Hence, the reason is also correct.
From the discussion above, we can conclude that both assertion and reason are correct and reason is the correct explanation for assertion

Hence, Option A is the correct option

Note: The atomic number of oxygen is 8 and hence the electronic configuration of oxygen is $1{s^2}2{s^2}2{p^4}$. Hence, we can see that the oxygen atom is short of two atoms to complete its octet in the valence shell. Hence, instead of bonding with any other atom or molecule to complete its octet, the oxygen atom combines with itself and forms a covalent diatomic molecule.