With the help clues provided in the image, can you find the 5 digit key?

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

Which English verb becomes past tense just by rearranging the letters?

You have two buckets of 11 liters and 6 litres.
How can you measure exactly 8 litres?

Who is generally closer to the kids, mom or dad?

(it's a funny riddle)

A pet show was happening in my locality. I went down along with my kids. In that show, I noticed that all except two of the entries were cats. All except two were dogs and all except two were Monkeys.

Can you find out how many of each animals were present in that pet show?

Solve the puzzle by telling what does below picture means.

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

An equation has been laid down using a few matchsticks. However, as you can see, the equation is not correct. Can you correct the equation if you are allowed to add or remove 5 matchsticks?

It can't be seen, can't be felt, can't be heard, and can't be smelt.
It lies behind stars and under hills, And empty holes it fills.
It comes first and follows after, Ends life, and kills laughter.
What is it?