Why do we preferably have round manhole covers and not square ones?

What does this say?

XLR8

A professor thinks of two consecutive numbers between 1 and 10.
'A' knows the 1st number and 'B' knows the second number

A: I do not know your number.
B: Nor do I know your number.
A: Now I know.

What are the four solutions for this?

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

_ _ _ IE _ _
_ _ _ IE _
_ _ IE _ _
_ _ IE _
_ _ _ _ IE

Like you see, some letters have gone missing from these words that contain the IE pair at some or the other place. The letters that will be used to fill the blanks are given below. Use them and form meaningful words. Can you do that?

A, C, D, F, H, K, L, M, N, N, O, R, R, S, S, S, T, T, Y and Y.

What does below science rebus mean?

Ag Ag Ag
Ag SPOON Ag
Ag Ag Ag

Find out the number of circles in the given picture having Illusion

Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?

Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet! Why?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?