Question

100 g of mercury (At. mass of mercury is 200) can be expressed as (This question has multiple correct options)
(a) 2 g atoms of mercury
(b) 1 g atoms of mercury
(c) 0.5 g atoms of mercury
(d) 0.5 moles of mercury

Answer 1

Hint: The number of moles of an atom is calculated by dividing the given mass of the atom to the atomic mass of the atom. Mole is equal to the gram atomic mass or gram molecular mass.

Complete step by step answer:
A mole of a compound is that amount of the substance whose mass is equal to gram formula mass (i.e., formula mass expressed in grams) or which contains Avogadro’s number ($6.023\text{ x 1}{\text{0}}^{23}$) of formula units.

The number of moles of a substance is calculated by dividing the given mass of the substance to the molecular mass of the substance.
$\text{Moles =}{\displaystyle \frac{\text{Given mass}}{\text{Molecular mass}}}$
In the question, the given mass of mercury is 100 g and the atomic mass of mercury is 200 g

So, the number of moles of mercury is,
$\text{Moles =}{\displaystyle \frac{\text{Given mass}}{\text{Molecular mass}}}={\displaystyle \frac{100}{200}}=0.5$
So, 0.5 moles of mercury is present.
This is also equal to 0.5 g atoms of mercury.
So, the correct answer is “Option C and D”.

Additional Information:
A mole is defined as that amount of the substance which has a mass equal to a gram atomic mass if the substance is atomic or gram molecular mass if the substance is molecular.
A mole is defined as that amount of the substance which contains Avogadro’s number ($6.023\text{ x 1}{\text{0}}^{23}$) of atoms if the substance is atomic or Avogadro’s number ($6.023\text{ x 1}{\text{0}}^{23}$) of molecules if the substance is molecular.

Note: The mole concept is useful in calculating the mass of a single atom and single-molecule. It is also used to calculate the number of molecules present in a given volume and calculation of the size of the individual atom.