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

In a university, a professor gave a set of three problems to the three brilliant students of his class. See the image for the questions.

It is deaf, Dumb and Blind!!!

Still, always tells the truth. What is it?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

When you stop to look, you can always see me. But if you try to touch me, you can never feel me. Although you walk towards me, I remain the same distance from you. What am I?

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?

I can be made.
I can be cracked.
I can be told.
I can be played.

Who am I?

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

A research team went to a village somewhere between the jungles of Africa. Luckily for them, they reached the day when quite an interesting custom was to be performed. The custom was performed once a year as they confirmed and was performed in order to collect the taxes from every male of the region.

The taxes were to be paid in the form of grains. Everyone must pay pounds of grain equaling his respective age. This means a 20-year-old will have to pay 20 pounds of grain and a 30-year-old will pay 30 pounds of grain and so on.

The chief who collects the tax has 7 weights and a large 2-pan scale to weigh. But there is another custom that the chief can weigh only three of the seven weights.

Can you find out the weights of the seven weights? Also, what is the maximum age of the man that can be weighed for the payment of taxes?

Bobby and Wilbur decided to take their respective car out of the garage and race. None of them cheated and they both stood at the start time and decided to cover a distance in full throttle. The first to reach the mark was to be declared the winner.

Upon reaching the finishing mark, they found out that Bobby's car was 1.2 times faster than Wilbur's. Now, Wilbur had reached the mark about 1 minute and 30 seconds later than Bobby. Bobby's car reached the mark of 60 MPH on average.

Can you calculate the distance between the starting mark and the final mark with the help of the given data?