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Q:

Temporary hardness is due to the presence of 

A) Calcium carbonate B) calcium bicarbonate
C) magnesium sulphate D) calcium sulphate
 
Answer & Explanation Answer: B) calcium bicarbonate

Explanation:

Temporary hardness is due to the presence of soluble bicarbonates of calcium and magnesium in water. Permanent hardness is due to the presence of sulphates and chlorides of calcium and magnesium.

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Q:

Harmful bacteria in drinking water cannot be destroyed by 

A) Chlorination B) boiling
C) adding caustic soda D) ozonisation
 
Answer & Explanation Answer: C) adding caustic soda

Explanation:

Water containing caustic soda cannot be used for drinking

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Q:

The function of nitrogen in air is 

A) to make air a moderate supporter of combustion B) to maintain the density of air constant
C) to prevent the hydrogen in air from exploding D) to reduce the poisonous nature of ozone in air
 
Answer & Explanation Answer: A) to make air a moderate supporter of combustion

Explanation:

If air contained all oxygen and no nitrogen, everything would have burnt off

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Q:

The process that takes place in the atom bomb is

A) nuclear fusion B) nuclear fission
C) radioactive disintegration D) chemical decomposition
 
Answer & Explanation Answer: B) nuclear fission

Explanation:

In the atom bomb, isotopes of uranium are  disintegrated with the release of a large amount of energy. Hence, the process is nuclear fission.

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Q:

Alum is used 

A) as an analgesic B) in the purification of water
C) as a fertilizer D) as a disinfectant
 
Answer & Explanation Answer: B) in the purification of water

Explanation:

Alum is a common alum, potassium aluminum sulphate K2SO4.Al2SO43.24H2O which makes colloidally suspended impurities in water such as clay to settle down.

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Exam Prep: AIEEE

Q:

An element which is preserved under water is 

A) sodium B) sulphur
C) red phosphorus D) white phosphorus
 
Answer & Explanation Answer: D) white phosphorus

Explanation:

White phosphorus undergoes spontaneous combustion when exposed to air. In order to prevent this spontaneous ignition, it is preserved under water. 

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Q:

Which of the following is called 'the King of Chemicals' ?

A) Nitric acid B) Hydrochloric acid
C) Silver nitrate D) Sulphuric acid
 
Answer & Explanation Answer: D) Sulphuric acid

Explanation:

Sulphuric acid is called the King of Chemicals because it is used in the preparation of a very large number of other useful chemicals such as hydrochloric acid, nitric acid, dyes, drugs etc. In fact the annual production of shulpuric acid in a country is a measure of the economy of the country.

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Q:

According to the modern Periodic Law, the properties of elements are periodic functions of their

A) volency B) atomic mass
C) number of neutrons D) atomic number
 
Answer & Explanation Answer: D) atomic number

Explanation:

Atomic number is the serial number of an element in the periodic classification of elements. It gives the number of protons and also the number of electrons in an atom.

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