Question

The number of atoms of hydrogen present in $1.5mole$ of ${H_2}O$ is:
A. $1N$
B. $2N$
C. $3N$
D. $0.5N$

Answer 1

The mole is the unit of measurement for amount of substance in the International System of Units (SI). A mole of a substance or a mole of particles is defined as exactly equal to $6.022 \times {10^{23}}$ particles, which is also known as the Avogadro number, which may be atoms, molecules, ions, or electrons. In short, for particles,$1{\text{ }}mol{\text{ }} = \;6.022 \times {10^{23}} = 1N$ .

Complete step by step answer:
As we know that a mole of any substance consists of Avogadro number (N) of particles in it and the particles consist of atoms, molecules, ions, etc. Thus, one mole of water will contain exactly the Avogadro number of molecules in it since water is a compound itself. The mole is essentially a count of particles. Usually the particles counted are chemically identical entities, individually distinct. For example, a solution may contain a certain number of dissolved molecules that are more or less independent of each other. However, in a solid the constituent particles are fixed and bound in a lattice arrangement, yet they may be separable without losing their chemical identity. Thus the solid is composed of a certain number of moles of such particles.
In the case of water (${H_2}O$ ), it consists of 3 atoms (two hydrogen and one oxygen).
$1mole$ of ${H_2}O$ consists of = $N$ molecules
$1.5mole$ of ${H_2}O$ consists of = $1.5N$ molecules
1 molecule of ${H_2}O$ consists of atoms of hydrogen = 2 atoms
Thus, the number of atoms of hydrogen present in $1.5mole$ of ${H_2}O$= $1.5N \times 2 = 3N$ atoms

So, the correct answer is Option C.

Note:
In yet other cases, such as diamond, where the entire crystal is essentially a single molecule, the mole is still used to express the number of atoms bound together, rather than a count of multiple molecules. Thus, common chemical conventions apply to the definition of the constituent particles of a substance, in other cases exact definitions may be specified.