Exams

There are six permanent members: China, Kazakhstan, Kyrgyzstan, Russia, Tajikistan, Uzbekistan. Soon India and Pakistan will also join it.

Coal is chemically complex fuel. Whenever it is burned, gases are given off and particles of ash, called "fly ash," are released. Release of sulfur from burning into the air. The sulfur in coal combines with oxygen to form sulfur dioxide, which can be a major source of air pollution if emitted in large enough quantities. This stuff comes back as acid rain when it attaches itself to a raindrop. 

Today, many of the effects of coal burning have been reduced significantly or eliminated. This is super-nasty and is only stopped by buying low-sulfur coal from Montana or Wyoming. The eastern power plants have to pay to move the coal from out west and this increases the price of power production.

Deleted files are not permanently removed from the hard drive or the computers memory. Before they are permanently removed from the system they are stored in Recycle Bin. Recycle Bin is a folder or directory where deleted items are temporarily stored. It is also called as trash.

Atoms are composed of Electrons, protons and Neutrons. Protons and Neutrons together called as Nuclei.

The given sentence 21 is 35 of what number means that 

21 is 35 % of what number

Let that number be P

=> 35P/100 = 21

35P = 2100

P = 2100/35 = 300/5 = 60

Hence, 21 is 35 of 60.