$$C_{V,m}=\frac{5}{2}R\\\mu(N_2)=0,25\frac{K}{atm}=\frac{1000}{4053}\frac{K}{bar}\\(1)\\\mu_T={\left(\frac{\partial H}{\partial p}\right)}_T=-C_{p,m}\cdot\mu\\C_{p,m}=C_{V,m}+R=\frac{5}{2}R+R=\frac{7}{2}R=\frac{7}{2}\cdot8,3145\frac{J}{mol\cdot K}\approx29,1\frac{J}{mol\cdot K}\\29,1\frac{J}{mol\cdot K}\cdot15\approx436,5\frac{J}{mol\cdot K}\\\mu_T=-C_{p,m}\cdot\mu=-436,5\frac{J}{mol\cdot K}\cdot\frac{1000}{4053}\frac{K}{bar}\approx-107,7\frac{J}{mol\cdot bar}\\(2)\\p=75atm\approx76bar\\dH=n{\left(\frac{\partial H}{\partial p}\right)}_T=-nC_{p,m}\mu dp=-nC_{p,m}\mu(p_2-p_1)=-15mol\cdot29,1\frac{J}{mol\cdot K}\cdot\frac{1000}{4053}\frac{K}{bar}\cdot(-76bar)\approx8185J$$