If two angles are linear pair, can they both be acute

No. A linear pair of angles is a pair that add up to 180 degrees. So their average is 90 degrees each. If they are not both 90-degree (right) angles, then one of them must be bigger than 90 ... an obtuse angle ... while the other one is less than 90 ... an acute angle.

No ... a linear pair is a straight line ... two acute angles wouldn't create a straight line