Practice Pakistan's most useful MCQs for competitive exams

CFC (chloro fluoro carbon) is very highly reactive in causing depletion of ozone layer in the atmosphere. Each atom of chlorine liberated from CFC is capable of decomposing ________________ molecules of ozone?

• (A)  102
• (B)  105
• (C)  109
• (D)  1015

Answer

Submitted By :Ali Uppal

The average thickness of ozone layer in stratosphere is about _______________ dobson unit (DU)?

• (A)  20
• (B)  230
• (C)  750
• (D)  1500

Answer

Submitted By :Ali Uppal

Noise level audible to audience sitting in the 5th row from the stage during a large orchestra show corresponds to about _______________ decibels?

• (A)  105
• (B)  135
• (C)  160
• (D)  185

Answer

Submitted By :Ali Uppal

Disinfection of water is done to remove ______________________?

• (A)  Color
• (B)  Bad taste
• (C)  Foul odour
• (D)  Bacteria

Answer

Submitted By :Ali Uppal

In water treatment plant, zeolite process is used to remove the _____________ of water?

• (A)  Acidity
• (B)  Alkalinity
• (C)  Hardness
• (D)  Iron & zinc

Answer

Submitted By :Ali Uppal

Salt content in sea water is about ______________ percent?

• (A)  0.5
• (B)  1
• (C)  3.5
• (D)  9.05

Answer

Submitted By :Ali Uppal

______________ is the process of killing organism in water ?

• (A)  Coagulation
• (B)  Sterilisation
• (C)  Disinfection
• (D)  Sedimentation

Answer

Submitted By :Ali Uppal

Fresh sewage is ______________ in nature?

• (A)  Acidic
• (B)  Neutral
• (C)  Alkaline
• (D)  Highly acidic

Answer

Submitted By :Ali Uppal

From pollution control point of view, the maximum permissible concentration of sulphur dioxide in atmospheric air is about ________________ ppm?

• (A)  5
• (B)  50
• (C)  500
• (D)  5000

Answer

Submitted By :Ali Uppal

Maximum permissible concentration (i.e. TLV) of DDT in public water supply system is _______________ micro gram (μ g)/litre?

• (A)  22
• (B)  42
• (C)  332
• (D)  1050

Answer

Submitted By :Ali Uppal