Final answer:
The relative molecular mass of gas b is 36.
Step-by-step explanation:
In order to find the relative molecular mass of gas b, we can use Graham's law of diffusion. According to Graham's law, the ratio of the rates of diffusion of two gases is proportional to the square root of the inverse of their molar masses. The equation can be written as:
(rate of diffusion of gas a) / (rate of diffusion of gas b) = sqrt(Mb / Ma)
Given that the ratio of the rates of diffusion is 1.5:1 and the relative molecular mass of gas a is 16:
1.5/1 = sqrt(Mb / 16)
Squaring both sides of the equation:
(1.5/1)^2 = (Mb / 16)
2.25 = (Mb / 16)
Mb = 2.25 * 16
Mb = 36
Therefore, the relative molecular mass of gas b is 36.