Solution:

The nail would be at the same height since trees grow at their tops.

Solution:

Pedro Rodrigues Filho was Mass Murderer.

Density multiplied by volume equals mass.
Therefore, Pedro Rodrigues Filho killing mass would mean Pedro Rodrigues Filho was a MASS murderer

Solution:

Throw the ball straight up in the air.

Solution:

When you mix bleach and ammonia [found in most cleaning products] it creates a deadly gas that can kill.

Solution:

H202 (Hydrogen peroxide) which is harmful and can cause death.

Solution:

In vacuum both will reach in same time.

whereas in case of air density medium it will depend on the surface area which is exposed to gravity opposing force.
gravity opposing force will increase as it is coming downwards and the amount of force is directly proportional to the area exposed to it.

Solution:

If you are thinking 5 times powerful, then you are in a completely wrong direction. The answer will be the square root of ten i.e. 3.16.

Thus if it was half a point higher on the Richter scale, the earthquake will be 3.16 times more powerful.

Solution:

Charcoal

Solution:

The iron brick will make the water level higher.

Explanation:
But on the contrary, in actual terms, none of them will help in rising the water. They will actually drop the water level. This is because, they have a large effect on the water level while in the boat but when they are dropped into the water. They will drop the water level. Iron brick being the lighter one will drop the water level less because it will have less effect on the water from the boat but will displace the equal amount of water as the gold when it is dropped into the water. Thus it can be said that it will make the water level higher.

Solution:

Fm.

These are the chemical elements whose atomic numbers are perfect squares.

1, 4, 9, 16, 25, 36, 49, 64, 81, 100

Solution:

The correct answer to this twisted problem is four times.

You can try solving the problem with the help of two coins and if you are unable to understand, you may even disassemble some clockwork to find out.

Now to explain it, it is evident that the small one will turn 3 times against the big one. The reason is because it has 8 teeth which is 1/3 of the big one (24). But now we want the big wheel to stop and the small one to turn around the big one. In this process, the small one will make an additional turn on its way around the big one. This makes a total of four turns.

Solution:

It is at the North Pole.

The winds are blowing towards the north till they reach the pole. The moment the pole is crossed, they are blowing towards south.

Solution:

Mercury

Solution:

An Echo