Sankalp NEET Full Test-1 Question-90 Solution

Question: 90. A compound X contains 32 \% of \mathrm{A}, 20 \% of B and remaining percentage of C. Then, the empirical formula of X is :

(Given atomic masses of \mathrm{A}=64 ; \mathrm{B}=40 ; \mathrm{C}=32 \mathrm{u} )

(1) A_{2} B C_{2}

(2) \mathrm{ABC}_{3}

(3) \mathrm{AB}_{2} \mathrm{C}_{2}

(4) \mathrm{ABC}_{4}

Answer: Option (2)

Explanation:

Let the total mass of the compound be 100 \ \mathrm{g}.

Mass of \mathrm{A} = 32 \ \mathrm{g}

Mass of \mathrm{B} = 20 \ \mathrm{g}

Mass of \mathrm{C} = 100 - (32 + 20) = 48 \ \mathrm{g}

Number of moles of \mathrm{A} = \dfrac{32}{64} = 0.5

Number of moles of \mathrm{B} = \dfrac{20}{40} = 0.5

Number of moles of \mathrm{C} = \dfrac{48}{32} = 1.5

The mole ratio of \mathrm{A} : \mathrm{B} : \mathrm{C} is

0.5 : 0.5 : 1.5

Dividing each term by the smallest value 0.5,

1 : 1 : 3

Hence, the empirical formula of the compound is \mathrm{ABC}_{3}.