Molar Heat Capacities of Ideal Gases

Nathaniel 2E
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Molar Heat Capacities of Ideal Gases

In question 8.31 from the 6th addition, the solutions manual explains that for monatomic ideal gases at constant pressure, the molar heat capacity is (5/2)R, and for a monatomic ideal gases at constant volume, the molar heat capacity is (3/2)R. Why can we assume these two claims to be true?

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Re: Molar Heat Capacities of Ideal Gases

$C{v} = \frac{3}{2}R$
$C{p} = \frac{5}{2}R$
These are the constants for molar heat capacities that we use when we are working with ideal gases. In that problem, it stated to assume that krypton behaves as an ideal gas, and so it is safe to assume that we can use Cv and Cp. R is the gas constant 8.314 J/(K*mol).