What does this rebus riddle means ?

What is the end of everything?

What demands an answer, but asks no questions

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

Different lights make me strange by changing me into different sizes. What am I?

What does this Rebus Picture mean?

The sum of a mother, her baby and her dog's weight is 170 Kg. How much does the baby weigh if the mother weighs 100 kg more than the combined weight of the baby and the dog, and the dog weighs 60 per cent less than the baby?

You walk into a room where there are three primates held in their respective cages:
1) A lion who is eating the flesh of a goat.
2) An orangutan who is playing with blocks.
3) A donkey who is sitting idle.

Who is the most intelligent primate in the room?

what does the below rebus means?

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?