Sawaal
20
Q:

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative 

Assertion(A)  : Graphite is slippery and used as a lubricant. 

Reason (R)    : Graphite has free electrons. 

A) Both A and R are true and R is the correct explanation of A. B) Both A and R are true but R is NOT the correct explanation of A.
C) A is true but R is false. D) A is false but R is true.

Answer:   B) Both A and R are true but R is NOT the correct explanation of A.



Explanation:

Graphite possesses a layer structure with two successive layers held by weak forces and able to slide over one another. So, graphite is slippery and this property finds its use as a lubricant. In graphite, each carbon atom is linked to three other carbon atoms while one electron in the carbon atom is delocalised. So, graphite has free electrons 

 

 

Subject: Assertion and Reason
Related Questions
Q:

An assertion (A) and a reason (R) are given below.

 

Assertion (A) : Agricultural activities are less on mountainous regions.

 

Reason (R) : Mountains have less fertile terrain and difficult weather conditions.

 

Choose the correct option.

 

A) Both A and R are true and R is the correct explanation of A B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false D) A is false, but R is true
 
Answer & Explanation Answer: A) Both A and R are true and R is the correct explanation of A

Explanation:
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Q:

An Assertion (A) and a Reason (R) are given below.

 

Assertion (A) : Beri-Beri is a viral infection.

 

Reason (R) : Vitamin deficiency causes diseases.

 

Choose the correct option.

 

A) A is false but R is true B) A is true but R is false
C) Both A and R are false D) Both A and R are true and R is the correct explanation of A
 
Answer & Explanation Answer: A) A is false but R is true

Explanation:
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Q:

Assertion(A) : Indus valley people knew the art of navigation.
Reason(R) : Indus valley seals indicate prevalence of overseas trade.

A) R is true but A is fale B) A is true but R is false
C) Both A and R are false D) R correctly explains A
 
Answer & Explanation Answer: D) R correctly explains A

Explanation:

The seals found at Indus valley sites gave evidance of overseas trade, which was possible only with the knowledge of art of navigation.
Thus, both A and R are true & R correctly explains A.

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10 6743
Q:

Assertion(A) : The steam engine was invented by James Watt.
Reason(R) : There was a problem of taking out water from flooded mines.

A) R correctly explains A B) R is true but A is fale
C) A is true but R is false D) Both A and R are false
 
Answer & Explanation Answer: A) R correctly explains A

Explanation:

The problem of pumping out water from the flooded mines provided the need of self-working engine, which led James Watt to invent the same.
Thus, both A and R are true & R correctly explains A.

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8 7384
Q:

Assertion(A) : The pouring of kerosene oil on stagnant pools helps to eradicate malaria.
Reason(R) : The kerosene oil is poisonous for the mosquitoes.

A) R correctly explains A B) R is true but A is fale
C) A is true but R is false D) Both A and R are false
 
Answer & Explanation Answer: C) A is true but R is false

Explanation:

The kerosene oil sprayed on the water provodes a thin cating and the larvae of the mosquitoes are prevented from coming up to breathe. Thus, they die.
Hence, A is true but R is false.

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Q:

Assertion(A) : Most of the Himalayan rivers are perennial.
Reason(R) : They are fed by melting snow.

A) R correctly explains A B) R is true but A is fale
C) A is true but R is false D) Both A and R are false
 
Answer & Explanation Answer: A) R correctly explains A

Explanation:

Most Himalayan rivers are perennial because they are fed by the melting snow throughout the year.
Thus, both A and R are true & R correctly explains A.

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11 3941
Q:

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative 

Assertion (A)  :  Eskimos reside in igloos. 

Reason (R)     :  No other material except snow is available. 

A) Both A and R are true and R is the correct explanation of A. B) Both A and R are true but R is NOT the correct explanation of A.
C) A is true but R is false. D) A is false but R is true.
 
Answer & Explanation Answer: C) A is true but R is false.

Explanation:

Eskimos live in snow houses called igloos because snow, being a bad conductor of heat, these houses are warm inside. 

 

 

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Q:

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative 

Assertion (A)  :  Pluto is the coldest planet 

Reason (R)     :  It receives slanting rays of- the sun. 

A) Both A and R are true and R is the correct explanation of A. B) Both A and R are true but R is NOT the correct explanation of A.
C) A is true but R is false. D) A is false but R is true.
 
Answer & Explanation Answer: C) A is true but R is false.

Explanation:

Pluto, being farthest from the sun, hardly gets the sun's rays. So, Pluto is the coldest planet. 

 

 

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