The density of helium is `0.1784 kg//m^(3)` at `STP` if a given mass of helium at `STP` is allowed to expand to `1.400` times of its initial volume by changing `P` and `T` compute its resultant density .

Explanation

`:' (w)/(V) = 0.1784kg //m^(3) = 0.1784g//` litreat `STP` It means
1 litre of gas at `STP` occupies `0.1784g` weight Now by changing `P` the `V` becomes `1.4 xx 1` litre where weight remains same
Thus ` d =(w)/(v) = (0.1784)/(1.4) = 0.1274 kg//m^(3)`
` =0.127g//`litre .