Replace the question mark with the correct number in the below-given picture?

No one wants to have it, but if one got it, he does not want to lose it. What is It?

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?

What month of the year has 28 days?

How can you make a TV, a bed, a dog, and a car liquid?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

Joseph buys three kinds of chocolates for 100 rupees. The first one is priced at 5 rupees, second one at 3 rupees and third one at 0.5 rupees.

If he bought 100 chocolates in total, how many pieces do you think he bought each chocolate?

Can you quickly find which two matchstick figures are identical?

Do you know who was buried in John's tomb?

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