Question

Calculate the number of moles and molecules present in 0.032 mg the methane ( C = 12 , H = 1)

Answer 1

$0.032\times {10}^{-3}$ g ${CH}_4$

M.W of ${CH}_4=16$

$\therefore$ Moles of ${CH}_4=\frac{givenwt.}{M.Wof{CH}_4}=\frac{0.032\times {10}^{-3}}{16}=2\times {10}^{-6}$

$\therefore$ molecules present $=2\times {10}^{-6}\times N_A$

$=2\times {10}^{-6}\times 6.022\times {10}^{23}=12.044\times {10}^{+17}$