The third shell of an atom can have a maximum of ______ electrons.

A thin spherical shell of internal diameter d is subjected to an internal pressure p. If $${\sigma _{\text{t}}}$$ is the tensile stress for the shell material, then thickness of shell is equal to

A

$$\frac{{{\text{pd}}}}{{{\sigma _{\text{t}}}}}$$

B

$$\frac{{{\text{pd}}}}{{2{\sigma _{\text{t}}}}}$$

C

$$\frac{{{\text{pd}}}}{{3{\sigma _{\text{t}}}}}$$

D

$$\frac{{{\text{pd}}}}{{4{\sigma _{\text{t}}}}}$$

In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass __________ through the heat exchanger.

A

Once

B

Twice

C

Thrice

D

Four times

In case of a shell and tube heat exchanger, the minimum shell thickness for carbon steel (inclusive of corrosion allowance) depends on shell diameter and is in the range of __________ mm.

A

3-5

B

5-11

C

8-15

D

12-18

Which of the following is the maximum number of electrons that can be present in M-shell?

A

2

B

8

C

18

D

32

In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell)

A

$$\frac{{\text{D}}}{5}$$ and D

B

$$\frac{{\text{D}}}{2}$$ and 2D

C

$$\frac{{\text{D}}}{4}$$ and 2D

D

D and 2D

In a thick cylindrical shell subjected to an internal pressure (p), the maximum radial stress at the inner surface of the shell is

A

Zero

B

p (tensile)

C

-p (compressive)

D

2p (tensile)

The maximum tangential stress in a thick cylindrical shell is always _________ the internal pressure acting on the shell.

A

Equal to

B

Less than

C

Greater than

D

None of these

The shell side pressure drop in a shell and tube heat exchanger is maximum for __________ baffle.

A

Disk and ring

B

Segmental

C

Orifice

D

Independent of the type of

How may valence electrons does a silicon atom have?

A

0

B

1

C

2

D

4

E

None of the above

Except Helium, all noble gases have how many electrons in the outermost shell?

A

4

B

8

C

6

D

10

The third shell of an atom can have a maximum of ______ electrons.

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