Q 21.
The mass number of a nucleus-
A)  total number of protons and neutrons
B)  always more than the atomic weigh
C)  always less than its atomic number
D)  None of these
Answer & Explanation Answer: total number of protons and neutrons

Explanation:

A) total number of protons and neutrons

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MCQ Type: Chemistry

Q 22.

The graphite rods in the nuclear reactor-

A)  produce neutrons
B)  react with U to release energy
C)  convert fast moving neutrons into thermal neutrons
D)  None of these
Answer & Explanation Answer: convert fast moving neutrons into thermal neutrons

Explanation:

C) convert fast moving neutrons into thermal neutrons

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MCQ Type: Chemistry

Q 23.

The manufacture of vanaspati from vegetable oil used-

A)  H_{2}
B)  co_{2}
C)  O_{2}
D)  None of these
Answer & Explanation Answer: H_{2}

Explanation:

A) H_{2}

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MCQ Type: Chemistry

Q 24.

The items amenable to detection by soft x-rays-

A)  genuine coins from counterfeit coins
B)  lead in bullets
C)  contrabands
D)  None of these
Answer & Explanation Answer: genuine coins from counterfeit coins

Explanation:

A) genuine coins from counterfeit coins.

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MCQ Type: Chemistry

Q 25.

In the froth floatation process used oil-

A)  Kerosene Oil
B)  Pine Oil
C)  Coconut Oil
D)  None of these
Answer & Explanation Answer: Pine Oil

Explanation:

B) Pine Oil

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MCQ Type: Chemistry

Q 26.

The number of waves in n x 10th Bohr’s orbit –

A)  n3
B)  n2
C)  n
D)  None of these
Answer & Explanation Answer: n

Explanation:

C) n

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MCQ Type: Chemistry

Q 27.

The main use of salt in the diet –

A)  increase the solubility of food particles in water
B)  taste of food better
C)  produce in small amounts the hydrochloric acid required for the digestion
D)  None of these
Answer & Explanation Answer: produce in small amounts the hydrochloric acid required for the digestion

Explanation:

C) produce in small amounts the hydrochloric acid required for the digestion

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MCQ Type: Chemistry

Q 28.

The number of water molecules present in a drop of water (volume 0.0018 ml) at room temperature is-

A)  4.84 x 1017
B)  6.023 x 1019
C)  6.023 x 1023
D)  None of these
Answer & Explanation Answer: 6.023 x 1019

Explanation:

B) 6.023 x 1019

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MCQ Type: Chemistry

Q 29.

The luster of a metal is due to-

A)  presence of free electrons
B)  its high density
C)  its high polishing
D)  None of these
Answer & Explanation Answer: presence of free electrons

Explanation:

A) presence of free electron

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MCQ Type: Chemistry

Q 30.

The monomer of polythene is

A)  Ethyl Alcohol
B)  Vinyl Chloride
C)  Ethylene
D)  None of these
Answer & Explanation Answer: Ethylene

Explanation:

C) Ethylene

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MCQ Type: Chemistry





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