Assertion: a : During hardening of steel, the component to be heat treated is strongly agitated in the quenching medium.Reason : r : The agitation breaks down the vapour barrier allowing the quench to proceed at a more rapid rate.

Both 'a' and 'r' are correct but 'r' is not correct reason of 'a'

Both 'a' and 'r' are correct and 'r' is the correct reason for 'a'

Assertion: a : During hardening of steel, the component to be heat treated is strongly agitated in the quenching medium.<br>Reason : r : The agitation breaks down the vapour barrier allowing the quench to proceed at a more rapid rate.

Arrange the following in terms of increasing severity of quench.
P. Oil quenching
Q. Water quenching
R. Water quenching with agitation
S. Brine quenching

A

[

A. P

B. Q

B

P

C

Q

Statement (I): Salts like sodium chloride, sodium hydroxide when added to water to use as quenching media, cooling rate of quenching media will be increased. Statement (II): When salts are added to water, during quenching, distortion and crack appearance in the quenched steel components reduces.

A

Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (1)

B

Both Statement (-) and Statement (II) are individually true tut Statement (II) is NOT the correct explanation of Statement (1)

C

Statement (I) is true but Statement (II) false

D

Statement (I) is false but Statement (II) is true

Consider the following statements: 1. The quenching of steel results in an increase in wear resistance, strength and hardness. 2. By the process of case hardening, hard wearing resistant surface is produced on mild steel. This is an effective method for low carbon steels because they cannot be hardened by the process of quenching. 3. When a metal is mixed with small atoms of non-metallic element in such a manner that invading atoms occupy interstitial positions in the metal lattice, an interstitial alloy results. What of the above statements are correct?

A

1 and 2 only

B

1 and 3 only

C

2 and 3 only

D

1, 2 and 3

An assertion and a reason are given below. Assertion: The phenomenon of nuclear fission generates great energy. Reason: The process in which a nucleus is broken into two parts is called nuclear fission. Choose the answer. A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion. B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion. C. Both Assertion and Reason are false. D. Assertion is true but Reason is false.

A

B

D

C

B

D

C

Directions : In each of the following questions a statement is given, followed by two conclusions. Give answer :

Statement : In view of the violent situation due to students' agitation the state government has decided to close down all the educational institutions in the state for two weeks with immediate effect.

Assumptions :
I. The students' agitation may subside after two weeks.
II. The students may not find a place to come further and continue agitation after the closure of the educational institutions.

A

Only assumption I is implicit

B

Only assumption II is implicit

C

Either I or II is implicit

D

Neither I nor II is implicit

E

Both I and II are implicit

Consider the following statements and choose the correct answer:
1. A direct proportionality exists between vapour pressure and the concentration of water vapour in the atmosphere
2. Relative humidity is an expression of the ratio of the actual vapour pressure of the atmosphere when saturated at the same temperature
3. A rise or fall in temperature with no change in vapour pressure will cause a drop or rise, respectively, in relative humidity
4. A rise or fall in vapour pressure with no change in temperature will be accompanied by a rise or fall, respectively, in relative humidity

A

1, 2, 3 and 4 are true

B

Only 3 and 4 are true

C

Only 2 and 4 are true

D

Only 1, 2 and 3 are true

The moon looks blood red during a total lunar eclipse because some of the sunlight passes through Earth’s atmosphere to reach the moon. As the white light breaks up while passing through the atmosphere, most of its blue-colored wavelengths are absorbed and scattered. The remaining red wavelengths light up the moon in blood-red color. Which of the following statements do not support the assertion of the above-given statement? I: The moon looks blood red during a total lunar eclipse as the white light breaks up due to the Earth's atmosphere where most of its red-colored wavelengths are absorbed. II: The moon looks blood red during a total lunar eclipse as the earth blocks the white light to travel to the moon.

A

Only I

B

Only II

C

Either I or II

D

Both I and II

E

Neither I nor II

What is the degree of agitation if bulk fluid velocity is 23.55 ft/min? (For 6 ft/min., degree of agitation = 1 and Degree of agitation varies from 0 to 10).

A

5

B

6

C

4

D

3

The only suitable method for hardening the low carbon steel is case hardening. Which of the following is a case hardening process?

A

Cyaniding

B

Sheardising

C

Spherodising

D

None of these

The cooling rate must be _________ the critical cooling rate for hardening of steel by quenching.

A

Higher than

B

Lower than

C

Equal to

D

Half of

Assertion: a : During hardening of steel, the component to be heat treated is strongly agitated in the quenching medium.
Reason : r : The agitation breaks down the vapour barrier allowing the quench to proceed at a more rapid rate.

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