Question

The density of the gaseous element is 5 times that of oxygen under similar conditions. if the molecule is triatomic . what will be its atomic mass?

Answer 1

under similar conditions, density is 5 times and the molecule is triatomic. I'd say the atomic mass is 10/3 times of oxygen atomic mass

Answer 2

The answe should be 53.33

Answer 3

PV = nRT
=> PV = mRT/M (m = mass of gas, M = molecular mass)
=> P = (m/V)RT/M
=> P = dRT/M (d = m/V = density)

So, P/RT = d/M
Under similar conditions, d/M remains constant
For oxygen, d/M = d(oxygen)/32 (Oxygen is diatomic => molecular mass = 2*atomic mass = 2*16)

For our element, d/M = 5d(oxygen)/(3*atomic mass)

These two are equal => 5/(3*atomic mass) = 1/32
=> atomic mass = 5*32/3 = 53.33 amu