Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

What jumps when it walks and sits when it stands?

What do you get if you add 2 to 100 four times?

Replace the question mark in the picture below.

In a contest, four fruits (an apple, a banana, an orange, and a pear) have been placed in four closed boxes (one fruit per box). People may guess which fruit is in which box. 123 people participate in the contest. When the boxes are opened, it turns out that 43 people have guessed none of the fruits correctly, 39 people have guessed one fruit correctly, and 31 people have guessed two fruits correctly.
How many people have guessed three fruits correctly, and how many people have guessed four fruits correctly

Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation. Conditions: Each must be used exactly once and no other numbers or symbols can be used.

If we tell you that there is a relation between the numbers and letters in the given figure, can you analyze it and find the missing letter in the last box?

There are 2 sand hourglasses.

The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?