What is free expansion?

Which among the following is $NOT$ an intensive property?

Define open,closed,and isolated systems with examples.

When $1 \ mol$ of a gas is allowed to expand freely in a vacuum,what is the work done during the process in Joules?

At $27\,^{\circ}C$,$1\, mole$ of an ideal gas expands reversibly and isothermally from $2\, atm$ to $1\, atm$. Then $\Delta H$ will be......$kJ$.

If $\Delta H$ is the change in enthalpy,$\Delta U$ is the change in internal energy,$N_P$ is the number of moles of products,and $N_r$ is the number of moles of reactants,then which of the following is correct for a gaseous reaction?