Question

The number of gram molecules of oxygen in $6.02 \times {10^{24}}$ molecules is:
A.$10g$ molecules
B.$5g$ molecules
C.$20g$ molecules
D.None

Answer 1

Hint: In one mole of atom there are $6.02 \times {10^{23}}$ molecules. If in the molecule we have to find the number of molecules then we have to multiply the Avogadro number by the molecule present in the compound.

Complete step by step answer:
First of all we will talk about the gram molecule, Avogadro number and atoms.
Atoms: It is the smallest unit of an element. The elements are made of the same kind of atoms. In the atoms there are three particles: electrons, protons and neutrons.
Electrons: They are the negatively charged particle having negligible mass. They move in the atoms outside the nucleus in a fixed orbit.
Protons: They are positively charged particles. They have mass. They are present in the nucleus (a special room in the atoms were neutrons and protons are present).
Neutrons: They have no charge but they have mass. They are also present in the nucleus along with protons.
Gram molecule: It is defined as the number of grams of the substance i.e. the molecular mass of the substance.
Atomic mass: It is defined as the total number of protons and neutrons present in the nucleus of an atom. It is represented by symbol A.
Atomic number: It is defined as the number of protons in the nucleus of an atom. It is represented by symbol Z.
In the given question it is given that we have to find the number of gram molecules of oxygen in $6.02 \times {10^{24}}$ molecules. We know that one gram molecule contains $6.02 \times {10^{23}}$ molecules. So the gram molecules in $6.02 \times {10^{24}}$ molecules will be \[\dfrac{{6.02 \times {{10}^{24}}}}{{6.02 \times {{10}^{23}}}} = 10\]. But we know that oxygen exists in molecular form as ${O_2}$. So, the total number of oxygen atoms will be $5$ gram molecules.

Hence option B is correct i.e. the number of gram molecules of oxygen in $6.02 \times {10^{24}}$ molecules is $5g$ molecules. .

Note:
In one mole of compound the gram equivalent is $6.02 \times {10^{23}}$molecules. Then if we want to find the gram equivalent for the atoms separately then divide the Avogadro number by the number of atoms present in the compound.