Calculate the number of particles in each of the following:
(i) 46 g of Na atoms (number from mass)
(ii) 8g `O_(2)` molecules (number of molecules from mass)
(iii) 0.1 mnole of carbon atoms (number from given moles)

Explanation

The number of `"atoms" // "molecules"= ("given mass")/("molar mass") xx "Avogadro number"`
i.e., `N= (m)/(M) xx N_(A)`
(i) `N= (46)/(23) xx 6.022 xx 10^(23)` [Molar mass of Na = 23 g]
`= 2 xx 6.022 xx 10^(23) ~~ 12.044 xx 10^(23)`
(ii) `N=(8)/(32) xx 6.022 xx 10^(23)` [Molar mass of `O_(2)` = 32 g]
`=(1)/(4) xx 6.022 xx 10^(23) ~~ 1.51 xx 10^(23)`
(iii) The number of atoms = `"number of moles" xx "Avogadro number"`
`:.` the number of carbon atoms = `0.1 xx 6.022 xx 10^(23) = 6.022 xx 10^(22)`