Can you guess the name of the month by looking the below rebus ?

What does the below rebus riddle means?

What's the only room from which no one can enter or leave

It is always ahead of me yet I can never see it. What is it?

We have four gears with below features=> Both Gear A and D has 60 teeth=> Gear B has 40 teeth=> Gear C has 20 teeth=> Every two minutes, Gear B makes 25 full turns.What is the relative speed of Gear A and Gear B?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

Replace the question mark with the correct number.

2 + 2= 4
3 + 3= 18
4 + 4= 48
5 + 5= ?

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.