JEE Main & Advanced Chemistry Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ Question Bank Self Evaluation Test - Some Basic Concepts of Chemistry

If \[3.01\times {{10}^{20}}\]molecules are removed from 98 mg of \[{{H}_{2}}S{{O}_{4}}\] then the number of moles of\[{{H}_{2}}S{{O}_{4}}\] left are

A) \[0.1\times {{10}^{-3}}\]

B) \[0.5\times {{10}^{-3}}\]

C) \[1.66\times {{10}^{-3}}\]

D) \[9.95\times {{10}^{-2}}\]

Correct Answer: B

Solution :

[b] Moles of \[{{H}_{2}}S{{O}_{4}}\]in 98 mg of \[{{H}_{2}}S{{O}_{4}}\]\[=\frac{1}{98}\times 0.098=0.001\]

Moles of \[{{H}_{2}}S{{O}_{4}}\]removes \[=\frac{3.01\times {{10}^{20}}}{6.02\times {{10}^{23}}}=0.5\times {{10}^{-3}}=0.0005\]

Moles of \[{{H}_{2}}S{{O}_{4}}\]left \[=0.001-0.0005=0.5\times {{10}^{-3}}\]