Question

Name two physical quantities which remains constant during uniform circular motion.

Answer 1

In my opinion Speed is the only quantity that remains constant.

Distance and all the vectors ( like velocity , displacement ,acceleration , etc ) changes .

Vectors changes in each time of reference because the object changes its direction constantly.

Answer 2

for horizontal circular motion centripetal acceleration and centripetal force remains constant for a constant angular velocity 
for vertical circular motion centripetal acceleration and force keeps on changing for a constant angular velocity