\(25\text{ cm}^3\) of a gas X contains Z molecules at \(15^\circ\text{C}\) and 75 mmHg. How many molecules will \(25\text{ cm}^3\) of another gas Y contain ...

The question is asking about the number of molecules of gas Y that will be present in a volume of 25cm³ at the same temperature and pressure as 25cm³ of gas X, which contains Z molecules. Since both gases are at the same temperature and pressure, we can assume that they have the same volume. Therefore, the volume of gas Y is also 25cm³. The number of molecules of gas Y can be calculated using the following formula: Number of molecules = (Volume of gas * Number of molecules of gas X) / Volume of gas X Plugging in the given values, we get: Number of molecules of gas Y = (25cm³ * Z) / 25cm³ = Z Therefore, the correct answer is option C, which is Z.