Answer:
Molar mass of the metal = 59.0 g/mol
Explanation:
Vapor pressure of water at
= 23.78 torr
We are given:
Total vapor pressure = 756.0 torr
Vapor pressure of hydrogen gas = Total vapor pressure - Vapor pressure of water = (756.0 - 23.78) torr = 732.22 torr
To calculate the amount of hydrogen gas collected, we use the equation given by ideal gas which follows:

where,
P = pressure of the gas = 732.22 torr
V = Volume of the gas = 255 mL = 0.255 L ( 1 mL = 0.001 L )
T = Temperature of the gas = ![25^oC=[25+273]K=298K](https://tex.z-dn.net/?f=25%5EoC%3D%5B25%2B273%5DK%3D298K)
R = Gas constant = 
n = number of moles of hydrogen gas = ?
Putting values in above equation, we get:

From the reaction shown below:-

1 mole of hydrogen gas is produced when 1 mole of the metal is reacted.
Also,
0.01 mole of hydrogen gas is produced when 0.01 mole of the metal is reacted.
Moles of the metal = 0.01 mol
Mass taken = 0.590 g
The formula for the calculation of moles is shown below:

Thus,

Molar mass of the metal = 59.0 g/mol