Questions

The two broad categories of software in a computer are

1. System software
2. Application software

System software controls how the system works and enables user to access all of the system hardware and application software

The OS, utility programs and drivers come under system software.

Application software are software used by the user to perform specific task. They are installed according to the user's requirements.

The word processor, web browser, players, spreadsheets etc... come under this application software.

Hindol Sengupta

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.