Is weightlifting aerobic exercise? Explain.

No!

Explanation:

if you are lifting heavy weights then it is considered as an intense workout. Your body can typically perform such intense exercises for less than 2 mins.

Such exercises use the available blood sugar and glycogen stores as energy source to perform the exercise. The glucose from these energy stores are burnt to provide energy to the body. During this process very less or  no oxygen is used. Hence it falls under anaerobic category.

During aerobic exercises, you will be using fat reserves to provide energy. To burn fat you will need oxygen.

Realistically, body always uses both of the above mentioned energy systems, but the percentage of which energy system is used more depends on the intensity of the workout.

No weightlifting is not aerobic exercise but rather anaerobic exercise. It involves quick burst of activity where aerobic exercise is constant during a longer period of time.