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Q:

Dust particles in the air of large industrial cities are removed by 

A) Sedimentation B) Electrophoresis
C) Tyndall effect D) Brownian movement

Answer:   B) Electrophoresis

Explanation:

Dust particles such as coal dust(smoke) are fine particle of a solid (carbon in the case of smoke) dispersed in air. They are colloidal systems and the particles are charged either positive or negative. In an applied electrical field, they are attracted towards the opposite electrodes. Movement of the particles towards the electrodes is known as 'electrophoresis'. Hence electrophoresis is applied to remove smoke within the chimeny itself without allowing it to escape into the air and cause nuisance.

Subject: Chemistry
Q:

Brass gets discoloured in air because of the presence of which of the following gases in air  ?

A) Hydrogen sulphide B) Oxygen
C) Nitrogen D) Carbon dioxide
 
Answer & Explanation Answer: A) Hydrogen sulphide

Explanation:
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Q:

Which of the following is a non metal that remains liquid at room temperature  ?

A) Chlorine B) Phosphorous
C) Bromine D) Helium
 
Answer & Explanation Answer: C) Bromine

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Q:

Permanent hardness of water is due to the presence of  ? 

A) Calcium sulphate B) Calcium bicarbonate
C) Sodium bicarbonate D) Magnesium bicarbonate
 
Answer & Explanation Answer: A) Calcium sulphate

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Q:

Select the correct statement (s).

A) When energy is transferred to the system from the surrounding as work, the surrounding do work on the system and the value of work (W) positive. B) When energy is transferred from the system to the surrounding as work, work is done on the surrounding and the value of W is negative.
C) Both (A) and (B) D) None of the above
 
Answer & Explanation Answer: C) Both (A) and (B)

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Q:

Triple point of water corresponds to

A) 1 atm, 0°C B) 1 atm, 0.01°C
C) 1 atm, 0 K D) 4.58 Torr, 0.01°C
 
Answer & Explanation Answer: D) 4.58 Torr, 0.01°C

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