What does below chemistry rebus means?

Look at the picture and find out which square is not linked with any of the other squares.

Rearrange the letters in "new door" to make one word.

Count the Triangle in the figure given below:

A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

Find The Missing Number In the Sequence.
6 25 64 ? 32 1

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

Every words stands for unique digit that makes the arithmetic equation true

SEVEN + SEVEN + SIX = TWENTY.

What are the digits ?

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?