• # question_answer52)   One mole of any substance contains $6.022\times {{10}^{23}}$ atoms/molecules. Number of molecules of  present in 100 mL of 0.02 M ${{H}_{2}}S{{O}_{4}}$ solution is : (a) $12.044\times {{10}^{20}}$ molecules (b) $6.022\times {{10}^{23}}$ molecules (c) $1\times {{10}^{23}}$ molecules (d) $12.044\times {{10}^{23}}$ molecules

(a) Number of moles of ${{H}_{2}}S{{O}_{4}}=\frac{MV}{1000}$ $=\frac{0.02\times 100}{1000}=0.002$ Number of molecules of ${{H}_{2}}S{{O}_{4}}=0.002\times 6.023\times {{10}^{23}}$ $=1.246\times {{10}^{21}}$