Correct answer is: (1) \(\frac{2}{3}\)
\(C_V=\frac{1\left(\frac{3R}{2}\right)+1\left(\frac{5R}{2}\right)}{2}\)
\(=\frac{8R}{4}=2R\)
\(C_P=\frac{1\left(\frac{5R}{2}\right)+1\left(\frac{7R}{2}\right)}{2}\)
\(=\frac{12R}{4}=3R\)
\(\frac{C_V}{C_P}=\frac{2R}{3R}\)
\(=\frac{2}{3}\)