When 2g of a gas A is introduced into an evacuated flask kept at `25^@C`, the pressure is found to be one atmosphere. If 3 g of another gas B are then added to the same flask, the total pressure becomes 1.5 atm. Assuming ideal gas behaviour, calculate the ratio of molecular weights `M_A : M_B`.

Explanation

To solve the problem, we will use the ideal gas law, which states:

\[ PV = nRT \]

Where:
- \( P \) = pressure
- \( V \) = volume
- \( n \) = number of moles
...