Chemistry Questions

Q:

Heated saw dust catches fire when a drop of concentrated nitric acid is added to it. This is due to

A) dehydration B) oxidation
C) reduction D) dehydrogenation
 
Answer & Explanation Answer: B) oxidation

Explanation:

Saw dust contains carbon which is oxidised to carbon  dioxide by concentrated nitric acid;

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Q:

The difference between a nuclear reactor and atomic bomb is that ___________

A) no chain reaction takes place in nuclear reactor while in the atomic bomb there is a chain reaction B) the chain reaction in nuclear reactor is controlled
C) the chain reaction in nuclear reactor is not controlled D) no-chain reaction takes place in atomic bomb while it takes place in nuclear reactor
 
Answer & Explanation Answer: B) the chain reaction in nuclear reactor is controlled

Explanation:
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Q:

An atom has 7 electrons in its M - shell and contains 18 neutrons in its nucleus. What is its mass number

A) 25 B) 27
C) 35 D) 43
 
Answer & Explanation Answer: C) 35

Explanation:

According to Bohr model, Each shell can occupy 2n2 electrons in their orbits where n=1,2,3.. for K,L,M,..

 

The atom has 2 electrons in k, 8 electrons in L and 7 electrons in M = 2 + 8 + 7 = 17

 

And given that its nucleus has 18 neutrons

 

=> its mass number = number of (electrons + neutrons ) = 17 + 18 = 35

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Q:

The bleeding of a wound is stopped by the application of ferric chloride because_____

A) Ferric chloride seals the blood vessels B) Blood starts flowing in the opposite direction
C) Blood reacts and a solid is formed which seals the blood vessels D) Blood is coagulated and the blood vessels are sealed
 
Answer & Explanation Answer: D) Blood is coagulated and the blood vessels are sealed

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Q:

Li3PO4 compound name?

A) Lithium perchlorate B) Lithium phyrite
C) Lithium phosphate D) None
 
Answer & Explanation Answer: C) Lithium phosphate

Explanation:

The given compund Li3PO4 name is Lithium phosphate.

 

Lithium phosphate is a white crystal at room temperature. It is slightly soluble in water.

It  can be used to produce glass, disk, colorful phosphor powder. It can also be used as a catalyst in some reactions.

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Q:

Which acid is produced when milk gets sour?

A) Lactic acid B) Acetic acid
C) Tartaric acid D) Butyric acid
 
Answer & Explanation Answer: A) Lactic acid

Explanation:
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Q:

The freezing point of water at 760mm pressure is

A) 0 K B) 273 K
C) 273 C D) -273 C
 
Answer & Explanation Answer: B) 273 K

Explanation:

K is degree kelvin

Zero K corresponds to -273  K = C + 273

The freezing point of water being 0 C, on the kelvin scale it is 0 C + 273 K

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Q:

The law of constant proportions was enunciated by

A) Dalton B) Berthelot
C) Avogadro D) Proust
 
Answer & Explanation Answer: D) Proust

Explanation:
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