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Q:

The main element used in the vulcanisation of rubber is

A) nickel B) copper
C) sulphur D) graphite
 
Answer & Explanation Answer: C) sulphur

Explanation:

In vulcanization, cruder rubber is heated with 3% sulphur at about for 1200C for 2-3 hours.

Vulcanised rubber is a vastly improved product.

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Exam Prep: AIEEE , GATE

Q:

Acute diabets  patients smell of 

A) acetone B) ether
C) ethyl alcohol D) methyl alcohol
 
Answer & Explanation Answer: A) acetone

Explanation:

Acute diabetes results in the formation of acetone in the body. Hence such patients smell of acetone.

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Q:

One of the ingredients of the paste on the side of a match box is 

A) Phosphorus pentaoxide B) Phosphorus trichloride
C) Phosphorus trisulphide D) Phosphorus trioxide
 
Answer & Explanation Answer: C) Phosphorus trisulphide

Explanation:

The paste applied to the side of a match box is a mixture of phosphorus trisulphide, glass powder (or sand) to cause friction and glue (binding material)

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Q:

The metal which reacts most violently with with cold water is

A) calcium B) sodium
C) magnesium D) potassium
 
Answer & Explanation Answer: D) potassium

Explanation:

Potassium reacts violently with water liberating hydrogen. The reaction is so violent that the liberated hydrogen catches fire.

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Q:

Water always contains hydrogen and oxygen in the ratio 1:8 by weight.This is in accordance with the 

A) Law of Multiple Proportions B) Law of Definite Proportion
C) Law of Conservation of mass D) Law of Reciprocal Proportions
 
Answer & Explanation Answer: B) Law of Definite Proportion

Explanation:

The Law of Definite Proportion states that the same compound, wherever found or however made, always contains the same elements combined together in the same fixede ratio by weight.

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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 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:

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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