Mass of hydrogen taken=1.12g,
number of moles that the cylinder can hold=1.12/1.008=1.11 moles,
mass of of substance X taken=26.64g,
as the number of moles that the cylinder can hold=1.11,
1.11=26.64/( molecular mass of substance x),
molecular mass of substance x=26.64/1.11=24u

**Solution:**

To calculate the gram molecular mass of gas X, we need to use the concept of the ideal gas equation and the concept of molar mass.

**1. Ideal Gas Equation:**

The ideal gas equation is given by:
PV = nRT

where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.

In this problem, we are given the condition of temperature and pressure to be similar for both hydrogen and gas X. Therefore, we can write the equation for both gases as:

P * V_H2 = n_H2 * R * T
P * V_X = n_X * R * T

where V_H2 and V_X are the volumes occupied by 1.12g of hydrogen and 26.64g of gas X, respectively.

**2. Calculation of Moles:**

To calculate the number of moles of each gas, we can use the formula:

n = m / M

where n is the number of moles, m is the mass, and M is the molar mass.

For hydrogen:
n_H2 = 1.12g / M_H2

For gas X:
n_X = 26.64g / M_X

**3. Equating the Equations:**

Since the temperature and pressure are the same for both gases, we can equate the two equations:

P * V_H2 = P * V_X
n_H2 * R * T = n_X * R * T

Dividing both sides of the equation by RT, we get:
n_H2 = n_X

**4. Substituting the Values:**

Substituting the values of n_H2 and n_X, we get:
1.12g / M_H2 = 26.64g / M_X

Cross-multiplying and rearranging the equation, we get:
M_X = (26.64g * M_H2) / 1.12g

**5. Calculation:**

To calculate the gram molecular mass of X, we need to know the molar mass of hydrogen (M_H2). The molar mass of hydrogen is approximately 2 g/mol.

Substituting the value of M_H2 into the equation, we have:
M_X = (26.64g * 2g/mol) / 1.12g

Simplifying the equation, we get:
M_X = 48g/mol

Therefore, the gram molecular mass of gas X is 48 g/mol.