What does below chemistry rebus means?

What number do you get when you multiply all of the numbers on a telephone's number pad?

You are mixing a mixture of cement and Sand with five gallons of water. You have a garden hose giving you all the water you need. The problem is that you only have a four-gallon bucket and a seven-gallon bucket and neither has graduation marks. Find a method to measure five gallons.

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

In the following picture, E is going to slide the object down and as per the terrain and the physics, the round object is going to travel all the way till the end. Now, can you analyze who all people will die when it happens?

In the given picture, in how many ways can you read the word "Tiger"?

What does this Rebus Picture means ?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?