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Q:

In the making of jewels, gold is usually mixed with 

A) zinc B) tin
C) copper D) aluminium
 
Answer & Explanation Answer: C) copper

Explanation:

In making jewels, gold is usually mixed with copper to make it little hard.

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Q:

In photography, the compound of nitrogen used is 

A) Potassium nitrate B) Silver nitrate
C) Ammonium carbonate D) Ammonium bicarbonate
 
Answer & Explanation Answer: B) Silver nitrate

Explanation:

Silver nitrate is the basic substance from which silver bromide is obtained. The photographic films are impregnated with the light sensitive AgBr.

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Q:

Which of the following acts both as oxidising and reducing agent?

A) nitric acid B) ammonia
C) nitrous acid D) nitrogen peroxide
 
Answer & Explanation Answer: C) nitrous acid

Explanation:

Nitrous acid act as an oxidising agent because it oxidises potassium iodide to iodine. It is also a reducing agent because it decolourises acidified potassium permanganate solution.

Nitric acid acts only as an oxidising agent

Ammonia acts only as a reducing agent

Nitrogen peroxide acts only as an oxidising agent.

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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:

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:

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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