Question

What is constant is R here and what is its value? ​

Answer 1

The gas constant is also known as the molar, universal, or ideal gas constant, denoted by the symbol R or R and is equivalent to the Boltzmann constant, but expressed in units of energy per temperature increment per mole, i.e. the pressure–volume product, rather than energy per temperature increment per particle

It’s value depends...

Since here the unit it KJ/mol it’s value is 8.314