The incorrect statement about carbon monoxide is-

1.	It reduces the oxygen-carrying ability of blood.
2.	The carboxyhaemoglobin (haemoglobin bound to CO) is less stable than oxyhaemoglobin.
3.	It is produced due to incomplete combustion.
4.	It forms carboxyhaemoglobin.

‘White lung cancer’ is caused by : 

1. Asbestos

2. Silica

3. Textiles

4. Paper

Incorrect statement among the following is: 

1. Oxides of sulphur, nitrogen, and carbon are the most widespread air pollutant.

2. pH of drinking water should be between 6.5 and 8.5.

3. Concentration of dissolved oxygen below 6 ppm is good for the growth of fish.

4. Clean water would have a BOD value of less than 5 ppm.

The aromatic compound that is present as particulate among the following is : 

1. Benzene

2. Toulene

3. Nitrobenzene

4. Polycyclic hydrocarbons

The oxygen present today in the atmosphere- 

1. Is a plant product.

2. Came from ozone.

3. Was present in the beginning.

4. Is produced by carbon dioxide.

Living in the atmosphere of CO is dangerous because it : 

1. Combines with O₂ present inside to form CO₂

2. Reduces organic matter of tissues.

3. Combines with haemoglobin and makes it incapable to absorb oxygen.

4. Dilutes the blood.

Biochemical oxygen Demand value less than 5 ppm indicates a water sample to be : 

1. Highly polluted.

2. Poor in dissolved oxygen.

3. Rich in dissolved oxygen.

4. Not suitable for aquatic life.

The chemical that is an excellent ‘green’ solvent as well as a greenhouse gas is: 

1. Methanol

2. CFCs

3. Carbon monoxide

4. Carbon Dioxide

Which, of the following, gases contributes  nearly 50 % to the green house effect (which, in turn, causes global warming) ?

1. SO₂

2. SO₃

3. CO₂

4. Water vapour

Ozone is a very toxic gas and a strong oxidizing agent. It is still useful for life on earth :

1. because it traps harmful UV-rays.

2. because it balances global warming.

3. because it traps harmful X-rays.

4. because it  traps harmful $\mathrm{\gamma }$-rays.