Nuclei Test

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Nuclei Test - 14

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Question 1
1 / -0

In carbon cycle of fusion, 4 protons combine to yield one alpha particle and

A
one positron

B
two positrons

C
ten positrons

D
three positrons

Solution

Carbon cycle [Carbon - Nitrogen Cycle] :
It consists of following reactions :
$_6^{12}C + _1^1H \Rightarrow _7^{13}N + Q_1$
$_7^{13}N \Rightarrow _6^{13}C + (_1^0e) + Q_2$
$_6^{13}C + _1^1H \Rightarrow _7^{14}N + Q_3$
$_7^{14}N + _1^1H \Rightarrow _8^{15}O + Q_4$
$_8^{15}O \Rightarrow _7^{15}N + (_1^0e) + Q_5$
$_7^{15}N + _1^1H \Rightarrow _6^{12}C+ _2^4He + Q_6$
On adding all these equations, we get
$4_1^1H \rightarrow _2^4He + 2(_1^0e) + Q$
(proton) ( $\alpha -$ particle) (positron) (energy)
where, $Q = Q_1+Q_2+Q_3+Q_4+Q_5+Q_6$ the value of Q as calculated from mass defect is 26.7 MeV.
Question 2
1 / -0

For a fast chain reaction, the size of $U^{235}$ block, as compared to its critical size, must be

A
greater

B
smaller

C
same

D
anything

Solution

In fast chain reaction neutron released in previous fission again strikes $^{235}U$ , So size of $^{235}U$ block should be greater than it's critical size.
Question 3
1 / -0

A nucleus with an excess of neutrons may decay with the emission of :

A
neutron

B
proton

C
electron

D
positron

Solution

An unstable atomic nucleus with an excess of neutrons may undergo $\beta^{-}$ decay, where a neutron is converted into a proton and electron.
Question 4
1 / -0

Bombardment of Beryllium by alpha particles resulted in the discovery of :

A
Proton

B
Nucleus

C
Neutron

D
Positron

Solution

Bombardment of Beryllium by alpha particles reaction is given as below:
$_4^9Be + _2^4He \rightarrow [_6^{13}C] \rightarrow _6^{12}C + _0^1n$
So, correct choice is option C.
Question 5
1 / -0

Which of the following property of an element never changes?

A
Valency

B
Atomic weight

C
Both A and B

D
None of the above

Solution

The atomic weight is a characteristic property of an element and can never vary.

The valency of an element can vary. For example, when the ion is in +2 and +3 oxidation state, its valency is 2 and 3 respectively.
Question 6
1 / -0

The binding energy of Helium nucleus is $28$ Mev. What is it's average binding energy per nucleon ?

A
102 MeV

B
56 MeV

C
14 MeV

D
7 MeV

Solution

$BE)_{Hc} = 28\ MeV$ $A \ of\ He = 4$

$BE)_{He} = \dfrac{28}{4} MeV$

$= 7\ MeV$
Question 7
1 / -0

Why high temperature is required for Nuclear fusion ?

A
All nuclear reactions absorb heat

B
The particles can not come together unless they are moving rapidly

C
The binding energy must be supplied from an external source

D
The mass defect must be supplied

Solution

Fusion reaction takes place at temperatures around $10^7k$ . It requires this high temperature so that nucleus start moving at rapidly speed, which in turn increases their kinetic, so that they overcome the repulsion between them and can come together.
Question 8
1 / -0

Fusion reaction take place at high temperature because

A
atoms are ionized at high temperature

B
molecules break up at high temperatures

C
nuclei break up at high temperature

D
kinetic energy is high enough to overcome repulsion between nuclei

Solution

Fusion reaction takes place at temperature about $10^7K$ .
It requires this high temperature so that nucleus are moving rapidly, so that they have high kinetic energy and can come together by overcoming repulsion between them.
Question 9
1 / -0

The value of 1 amu is equal to:

A
$1.66\times 10^{-8}g$

B
$1.66\times 10^{-4}g$

C
$1.66\times 10^{-16}g$

D
$1.66\times 10^{-24}g$

Solution

One an amu is $\dfrac{1}{12}$ of the mass of one carbon-12 atom.

It is equal to $\dfrac{1}{N_A}$

$= \dfrac{1}{6.022\times10^{23}} = 1.66 \times 10^{-24} g$ .
Question 10
1 / -0

Fusion reaction takes place at very high temperature because

A
atoms are ionised at high temperatures

B
molecules breakup at high temperature

C
nuclei break up at high temperature

D
kinetic energy is high enough to overcome repulsion between nuclei

Solution

Fusion reactions takes place at temperature about $10^7K$ it requires this high temperature so that nucleus are moving at very high speed, so that they have high kinetic energy and can overcome the repulsion between nuclei and come together.

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Nuclei Test - 14

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Nuclei Test - 14

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SHARING IS CARING

Question 1

one positron

two positrons

ten positrons

three positrons

Solution

Question 2

greater

smaller

same

anything

Solution

Question 3

neutron

proton

electron

positron

Solution

Question 4

Proton

Nucleus

Neutron

Positron

Solution

Question 5

Valency

Atomic weight

Both A and B

None of the above

Solution

Question 6

102 MeV

56 MeV

14 MeV

7 MeV

Solution

Question 7

All nuclear reactions absorb heat

The particles can not come together unless they are moving rapidly

The binding energy must be supplied from an external source

The mass defect must be supplied

Solution

Question 8

atoms are ionized at high temperature

molecules break up at high temperatures

nuclei break up at high temperature

kinetic energy is high enough to overcome repulsion between nuclei

Solution

Question 9

1.66×10−8g1.66\times 10^{-8}g1.66×10−8g

1.66×10−4g1.66\times 10^{-4}g1.66×10−4g

1.66×10−16g1.66\times 10^{-16}g1.66×10−16g

1.66×10−24g1.66\times 10^{-24}g1.66×10−24g

Solution

Question 10

atoms are ionised at high temperatures

molecules breakup at high temperature

nuclei break up at high temperature

kinetic energy is high enough to overcome repulsion between nuclei

Solution

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$1.66\times 10^{-8}g$

$1.66\times 10^{-4}g$

$1.66\times 10^{-16}g$

$1.66\times 10^{-24}g$