Question

One mole of any substance contains $6.022\times {10}^{23}$ atoms/molecules. Number of molecules of $H_{2}S{O}_4$ present in 100 mL of $0.02M{H}_{2}S{O}_4$ 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

Answer 1

(a)

One mole of any substance contains $6.022\times {10}^{23}$ atoms/molecules.

Hence, Number of millimoles of $H_{2}S{O}_4$

= molarity $\times$ volume in mL

$=0.02\times 100=2$ millimoles

$=2\times {10}^{-3}mol$

Number of molecules = number of moles $\times N_A$

$=2\times {10}^{-3}\times 6.022\times {10}^{23}$

$=12.044\times {10}^{20}$ molecules