What does the below rebus riddle means?

I cannot talk, but I always reply when spoken to. What am I?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Find the next number in the series below

21 32 54 87 131 ?

A cricket has 6 legs, a squirrel has 4 legs and a spider has 8 legs.

In a local zoo, it was found that the total number of legs is 612. Also, there are equal number of each of the above animals/insects.

Can you find out how many animals are there in the zoo?

Alex is stranded on an island covered in forest.
One day, when the wind is blowing from the west, lightning strikes the west end of the island and sets fire to the forest. The fire is very violent, burning everything in its path, and without intervention the fire will burn the whole island, killing the man in the process.

There are cliffs around the island, so he cannot jump off.

How can the Alex survive the fire? (There are no buckets or any other means to put out the fire)

What goes through cities and fields, but never moves?

Make a sentence consisting of three words that have the whole alphabet.

You order chicken wings at KFC in the boxes of 6, 9 and 20. What is the largest number of wings that you cannot obtain by buying in any combination of the boxes?