P is False because of the number of leaves of a decision tree which sort $5$ numbers is $5!$ and the height of a tree is atleast $log(5!)$. We need atleast $7$ comparisons.
Q is False because of auxiliary sorting routine in radix sort needs to be stable, meaning that numbers with the same value appear in the output array in the same order as they do appear in the input array. Heapsort is not stable. It does operate in place, meaning that only a constant number of elements of the input array are ever stored outside the array