Question

Arrange the following in the decreasing order of number of oxygen atoms.

(A) $0.5$ moles of sulphuric acid

(B) $1$ mole of water

(C) $0.25$ moles of nitric acid

(D) $2$ moles of hydrogen peroxide

(E) $1$ mole of ferric oxide

• A. DABEC
• B. BAECD
• C. DEABC
• D. BCDEA

Answer 1

The correct option is C

DEABC

Explanation of correct option:

We know that one mole of oxygen atoms will contain $6.022\mathrm{x}{10}^{23}$oxygen atoms. So, the more the number of moles of oxygen atoms, the more will be the number of oxygen atoms. Thus, we will calculate the number of moles of oxygen atoms in each case.

Calculation of the number of moles of oxygen atoms in different cases:

(A) $0.5$ moles of ${\mathrm{H}}_2{\mathrm{SO}}_4$

• $1$ molecule of Sulphuric acid (${\mathrm{H}}_2{\mathrm{SO}}_4$) contain $4$ $\mathrm{O}$ atoms. So, $0.5$ moles of Sulphuric acid contain $2$ moles of $\mathrm{O}$ atoms.

(B) $1$mole of water(${\mathrm{H}}_2\mathrm{O}$) will contain $1$ mole of $\mathrm{O}$ atoms.

(C) $0.25$ moles of ${\mathrm{HNO}}_3$

• $1$ molecule of ${\mathrm{HNO}}_3$contains $3$ $\mathrm{O}$ atoms. So, $0.25$ moles of ${\mathrm{HNO}}_3$contain $0.75$ moles of $\mathrm{O}$ atoms.

(D) $2$ moles of Hydrogen peroxide(${\mathrm{H}}_2{\mathrm{O}}_2$)

• $1$mole of Hydrogen peroxide will contain $2$ moles of $\mathrm{O}$ atoms. So, $2$ moles of Hydrogen peroxide $4$ moles of $\mathrm{O}$ atoms.

(E) $1$ mole of ferric oxide (${\mathrm{Fe}}_2{\mathrm{O}}_3$) will contain $3$ moles of $\mathrm{O}$ atoms.

So, the correct decreasing order is EDABC.

Hence, the correct option is (C).