Nuclei Test

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Nuclei Test - 21

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Weekly Quiz Competition

Question 1
1 / -0

$$N$$ atoms of a radioactive element emit $$n$$ number $$\alpha $$- particle per second. Mean life of the elements
in second is :

A
$$\dfrac{n}{N}$$

B
$$\dfrac{N}{n}$$

C
0693$$\dfrac{N}{n}$$

D
0.693$$\dfrac{n}{N}$$

Solution

Number of disintegrations per second= dN/dt = n = Nλ

λ = n/N , where λ is the decay constant

Mean life = 1/λ = N/n

Option B is correct.
Question 2
1 / -0

The binding energy per nucleon of iron atom is approximately.

A
13.6 eV

B
8.8 MeV

C
infinity

D
10 MeV

Solution

The maximum binding energy per nucleon occurs at around mass number $$A=50$$, and corresponds to the most stable nuclei. Iron nucleus $${{F}^{56}}$$ is located close to the peak with a binding energy per nucleon value of approximately $$8.8\,MeV$$ . It’s one of the most stable nuclides that exist.
Question 3
1 / -0

During $$\beta^-$$ emission:

A
a neutron in the nucleus decays emitting an electron

B
an atomic electron is ejected

C
an electron already present within the nucleus is ejected

D
a part of the binding energy of the nucleus is converted into an electron

E
a proton in the nucleus decays emitting an electron

Solution

$$\beta^-$$ emission is due to decay of neutron in the nucleus $$n\rightarrow p+e^-$$.
Question 4
1 / -0

When a radioactive substance is kept in a vessel, the atmosphere around it is rich with

A
$$Ne$$

B
$$Ar$$

C
$$Xe$$

D
$$He$$

Solution

A radioactive substance will emit $$\alpha $$ radiation and alpha radiation is nothing but $$nucleus $$ of $$Helium$$ atom so the atmosphere will be rich with $$He$$
Option D is correct.

All other options are the example of inert gases and any radioactive material doesn't emit inert gases.
Question 5
1 / -0

A nucleus of element X is represented as $$_{ 26 }^{ 56 }{ X }$$
Which is an isotope of element X?

A
$$_{ 56 }^{ 26 }{ X }$$

B
$$_{ 26 }^{ 54 }{ X }$$

C
$$_{ 24 }^{ 56 }{ X }$$

D
$$_{ 28 }^{ 54 }{ X }$$

Solution

Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom.

Since , the isotopes has same number of proton , so , Option (B) is correct as it has same number of proton i.e. $$26$$
Question 6
1 / -0

The neutron was discovered by

A
Marie Curie

B
Pierree Curie

C
James Chadwick

D
Rutherford

Solution

James Chadwick discovered the neutron.
Question 7
1 / -0

A proton and a neutron combine to give a deuterium nucleus.If $$m_{o}$$ and $$m_{p}$$ be the mass of neutron and proton respectively, then mass of deuterium nucleus is

A
equal to $$m_{o}$$+$$m_{p}$$

B
more than $$m_{o}$$+$$m_{p}$$

C
less than $$m_{o}$$+$$m_{p}$$

D
can be less than or more than $$m_{o}$$+$$m_{p}$$

Solution

The energy released during this during this in form of gamma photon comes from mass defect. (i.e., $$E=mc^2$$, where $$m$$ is the mass defect). The mass of the deuterium nucleus (2.01355 u) is less than the sum of the masses of the proton (1.00728 u) and the neutron (1.00866 u), which is 2.01594 u.
Question 8
1 / -0

In a nuclear reaction some mass converts into energy. In this reaction total B.E of reactants when compared with that of products is:

A
always greater

B
always less

C
either greater or less

D
always equal

Solution

The difference in mass between the separate particles and the nuclide is called the mass defect. This 'missing mass' accounts for the binding energy..
Binding energy of the products is always greater than the binding energy of the reactants and the difference is released as energy.
Question 9
1 / -0

$$M, M$$$$_{n}$$ and $$M$$$$_{p}$$ denotes the masses of a nucleus of $$_{Z}X^{A}$$, a neutron, and a proton respectively. If the nucleus is separated into its individual protons and neutrons then,

A
$$M=(A-Z)M_{n}+ZM_{p}$$

B
$$ M=ZM_{n}+(A-Z)M_{p}$$

C
$$M>(A-Z)M_{n}+ZM_{p}$$

D
$$ M<(A-Z)M_{n}+ZM_{p}$$

Solution

$$ Mc^{2} + Binding energy = [( A-Z)Mn + Z Mp] c^{2}$$
Therefore, mass of nucleus is less than total mass of its free nucleons.
Question 10
1 / -0

The nucleus finally formed in fusion of the proton in a proton cycle is that of:

A
Helium

B
Deuterium

C
Carbon

D
Hydrogen

Solution

Proton - Proton cycle :
The thermonuclear reactions involved are :
$$2(_1^1H) + 2(_1^1H) \Rightarrow 2(_1^2H) + 2(_1^0e) + Q_1$$
$$2(_1^2H) + 2(_1^1H) \Rightarrow 2(_2^3He) + Q_2$$
$$2(_2^3He) \Rightarrow (_2^4He) + 2(_1^2H) + Q_3$$
On adding up these reactions, we obtain
$$4(_1^1H) \Rightarrow _2^4He + 2(_1^0e) + Q$$
where, $$Q = Q_1 + Q_2 + Q_3$$ is the total energy involved in the fusion of 4 hydrogen nuclei to form Helium nucleus. The value of Q as calculated from mass defect comes out to be 26.7 MeV.

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Nuclei Test - 21

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Nuclei Test - 21

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Question 1

$$\dfrac{n}{N}$$

$$\dfrac{N}{n}$$

0693$$\dfrac{N}{n}$$

0.693$$\dfrac{n}{N}$$

Solution

Question 2

13.6 eV

8.8 MeV

infinity

10 MeV

Solution

Question 3

a neutron in the nucleus decays emitting an electron

an atomic electron is ejected

an electron already present within the nucleus is ejected

a part of the binding energy of the nucleus is converted into an electron

a proton in the nucleus decays emitting an electron

Solution

Question 4

$$Ne$$

$$Ar$$

$$Xe$$

$$He$$

Solution

Question 5

$$_{ 56 }^{ 26 }{ X }$$

$$_{ 26 }^{ 54 }{ X }$$

$$_{ 24 }^{ 56 }{ X }$$

$$_{ 28 }^{ 54 }{ X }$$

Solution

Question 6

Marie Curie

Pierree Curie

James Chadwick

Rutherford

Solution

Question 7

equal to $$m_{o}$$+$$m_{p}$$

more than $$m_{o}$$+$$m_{p}$$

less than $$m_{o}$$+$$m_{p}$$

can be less than or more than $$m_{o}$$+$$m_{p}$$

Solution

Question 8

always greater

always less

either greater or less

always equal

Solution

Question 9

$$M=(A-Z)M_{n}+ZM_{p}$$

$$ M=ZM_{n}+(A-Z)M_{p}$$

$$M>(A-Z)M_{n}+ZM_{p}$$

$$ M<(A-Z)M_{n}+ZM_{p}$$

Solution

Question 10

Helium

Deuterium

Carbon

Hydrogen

Solution

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