Acid rain is caused due to the pollution of environment by:

• Carbondioxide and Nitrogen
• Carbon monoxide and Carbondioxide
• Ozone and Methane
• Some oxide of Nitrogen and Sulpher
Correct Option: D  [ Some oxide of Nitrogen and Sulpher ]

Remark: Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air

As per Bureau of Indian Standards (BIS) for drinking water acceptable limit for total hardness as CaCO3 is

• 100 mg/l
• 200 mg/l
• 300 mg/l
• None of these
Correct Option: B  [ 200 mg/l ]

Remark:

The most abundant metal in the Earth crust is:

• zinc
• copper
• aluminium
• iron
Correct Option: C  [ aluminium ]

Remark:

Fathom is unit of:

• Depth
• Distance
• Frequency
• Sound
Correct Option: A  [ Depth ]

Remark:

A piece of ice is ?oating in a beaker containing water. When whole of the ice melts:

• the level of water will come down.
• the level of water will come up.
• the level of water will first rise and then fall.
• the level of water will remain the same.
Correct Option: D  [ the level of water will remain the same. ]

Remark:

The technique of 'DNA sequencing' was discovered by:

• H. G. Khorana
• Watson and Crick
• Frederick Sanger
• E. M. Southern
Correct Option: B  [ Watson and Crick ]

Remark:

One of the constitutes of tear gas is:

• Ethane
• Ethanol
• Ether
• Chloropicrin
Correct Option: D  [ Chloropicrin ]

Remark:

Ocean thermal energy is due to:

• tides in the ocean
• pressure difference at different levels in the ocean
• temperature difference at different levels in the ocean
• energy stored by waves in the ocean
Correct Option: C  [ temperature difference at different levels in the ocean ]

Remark:

Which of the following colours is not a primary colour ?

• Red
• Yellow
• Green
• Blue
Correct Option: B  [ Yellow ]

Remark:

Which one of the following has the highest fuel value ?

• Hydrogen
• Charcoal
• Natural gas
• Gasoline
Correct Option: A  [ Hydrogen ]

Remark: "Hydrogen" has the highest calorific value among commonly used fuels because it has a very high energy content, undergoes complete combustion, has a high heat of combustion, and can be used in various applications.