Mixing of two gases

Consider two containers, one holding $1kg$ of argon at $300K$ and the other holding $1kg$ of krypton at $500K.$ In each vessel, the average microscopic speed is given by $\frac{?}{\text{b}\text{a}\text{r}}(v)=\sqrt[\phantom{2}]{8k_b\frac{T}{}m}$

$($a$)$ For which species is the average microscopic speed the highest?

$($b$)$ Consider bringing these two containers together and mixing the nitrogen and krypton without any net volume change or heat transfer to the surroundings. What is the total internal energy contained within the vessel?

$($c$)$ What is the final temperature?

$($d$)$ Is the mean speed of the argon and krypton higher or lower than before mixing, respectively?