In water pollution, industries are said to be the _____.

1. 1. Lines sources
   2. Point Sources
   3. Area sources
   4. None of these

The gas associated with global warming is _____.

1. 1. CO2
   2. H2S
   3. CH4
   4. SO2

Which of the following does not cause soil erosion?

1. 1. Wind
   2. Overgrazing
   3. Sun
   4. Water

Which are air polutants?

1. 1. Aerosols
   2. Sewage
   3. DDT
   4. Fertilizers

The Pakistani population receives the largest dose of ionizing radiation from _____.

1. 1. Natural sources
   2. Fallout from nuclear weapons testing
   3. Nuclear medicine
   4. Nuclear power plants

One of the main functions of the earth’s ozone layer is to _____.

1. 1. Prevent global warming
   2. Filter out ultraviolet rays
   3. Absorb pollution
   4. All of the above

The Ozone layer protects the earth from rays sent by the sun _____.

1. 1. Ultraviolet rays
   2. Infrared rays
   3. Gamma rays
   4. Radioactive reays

The ozone layer is present in atmosphere above earth. The stratum (layer) of atmosphere in which ozone layer lies is called as _____.

1. 1. Exosphere
   2. Mesosphere
   3. Stratosphere
   4. Ionosphere

Which of the following does not vary predictably with the depth of the aquatic environment?

1. 1. Salinity
   2. Temperature
   3. Penetration by sunlight
   4. None of these

Which of the following Disease is water borne?

1. 1. Typhoid
   2. Tuberculosis
   3. Hepatitis B
   4. Scurvy