Which of the following will weigh maximum amount?
(a). `20 g` iron, (b) `1.2 g` atom of `N`,
(c ) `1xx10^(23)` atoms of carbon,
(d) `1.12 litre` of `O_(2) at STP`.

Explanation

(a) Mass of iron `= 20 g`
(b) Mass of `1.2 g`-atom of `N = 14xx1.2= 16.8 g`
(c ) Mass of `1xx10^(23)` atoms of `C=(12xx1xx10^(23))/(6.023xx10^(23))`
`1.99 g`
(d) Mass of `1.12` litre of `O_(2) at STP=(32xx1.2)/(22.4)= 1.6 g`
Thus `20 g` iron has maximum weight.