Nuclei Test

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Nuclei Test - 55

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Weekly Quiz Competition

Question 1
1 / -0

A radioactive sample has an initial activity of $$50\ dpm$$, $$20$$ minute later, the activity is $$25\ dpm$$. How many atoms of the radioactive nuclide were there originally ?

A
$$20$$

B
$$1000$$

C
$$1443$$

D
$$2$$

Solution
Question 2
1 / -0

What is the binding energy per nucleon of $$_{6}C^{12}$$ nucleus?
Given : mass of $$C^{12}(m_c)=12.000\ u$$
mass of proton $$9M_p)=1.0078\ u$$
mass of neutron $$(m_n)=1.0087\ u$$ and
$$1\ amu=931.4\ MeV$$

A
$$5.26\ MeV$$

B
$$10.11\ MeV$$

C
$$15.65\ MeV$$

D
$$7.68\ MeV$$

Solution
Question 3
1 / -0

$$O^{19}\longrightarrow F^{19}+e+\bar v$$
In this decay, the rest mass energy of $$O^{19}$$ and $$F^{19}$$ are $$17692.33\ MeV$$ and $$17687.51\ MeV$$ respectively. The $$Q$$ factor of the decay is :

A
$$4.82\ MeV$$

B
$$7\ MeV$$

C
$$17.69\ MeV$$

D
$$none\ of\ these$$

Solution
Question 4
1 / -0

The atomic mass of $$B^{10}$$ is $$10.811\ amu$$. The binding energy of $$B^{10}$$ nucleus is [ Given: The mass of electron is $$0.0005498\ amu$$, the mass of proton is $$m_p=1.007276\ amu$$ and the mass of neutron is $$m_n=1.008665\ amu$$]:

A
$$-678.272\ MeV$$

B
$$678.932\ MeV$$

C
$$378.932\ MeV$$

D
$$none\ of\ these$$

Solution
Question 5
1 / -0

$$\alpha,\beta$$ and $$\gamma$$ radiations come out of a rodiactive substance

A
when it is heated

B
when put in atomic reactor

C
spontaneously

D
under pressure

Solution

Alpha and beta particles consist of matter, and gamma rays are bursts of energy. The type of radiation emitted depends on the radioactive substance.
An alpha particle is made up of two protons and two neutrons bound together. Beta particles are high energy electrons. Gamma rays are waves of electromagnetic energy or photons.
From this, it is clear that these three radiations come out of a radioactive substance spontaneously.
Hence option c is the right answer.
Question 6
1 / -0

Radioactivity can be effected by :

A
temperature

B
pressure

C
radiation

D
all of these

Solution

Exposure to very high levels of radiation, such as being close to an atomic blast, can cause acute health effects such as skin burns and acute radiation syndrome (“radiation sickness"). It can also result in long-term health effects such as cancer and cardiovascular disease.
Therefore Radioactivity can be affected by radiation itself.
Hence Option C is the right answer.
Question 7
1 / -0

The binding energy of $$Na^{23}$$ is [ Given : Atomic mass of $$22.9898\ amu$$ and that of $$^1 H_1$$ is $$1.00783\ amu$$]:

A
$$931\ MeV$$

B
$$186.54\ MeV$$

C
$$5.38\ MeV$$

D
$$none\ of\ these$$

Solution
Question 8
1 / -0

A binding energies per nucleon for a deuteron and an $$\alpha-$$ particle are $$x_1$$ and $$x_2$$ respectively. What will be the energy $$Q$$ released in the reaction?
$$_{1}H^{2}+_{1}H^{2}\longrightarrow _{2}He^{4}+Q$$

A
$$4(x_1+x_2)$$

B
$$4(x_2-x_1)$$

C
$$2(x_1+x_2)$$

D
$$2(x_2-x_1)$$

Solution

The correct option is B.

Given,
A binding energies per nucleon for deuteron and an $$\alpha $$- particle are $$x_1$$ and $$x_2$$ respectively.
The provided reaction is
$${H_{1}}^{2}+{H_{1}}^{2}\rightarrow {H_{2}}^{4}+Q$$

We are required to find out the energy released in the reaction i..e Q value.
The number of deuterons is $$2$$.
The number of nucleons for $$2$$ deuteron is $$4$$.
The number of nucleons for $$2$$ helium is $$4$$.
The energy for $${H_{1}}^{2}$$ is $$4x_1$$.
The energy for $${H_{2}}^{4}$$ is $$4x_2$$
Therefore, the energy released is calculated as
$$Q$$ = $$4\left ( x_2-x_1 \right )$$.
Hence, the required answer is $$Q$$ = $$4\left ( x_2-x_1 \right )$$.
Question 9
1 / -0

The critical mass of fissionable uranium $$235$$ can be reduced by:

A
surrounding it by neutron absorbing material

B
surrounding it by neutron reflecting material

C
heating the material

D
adding impurities

Solution
Question 10
1 / -0

As the mass number A increases, the binding energy per nucleon in a nucleus

A
increases

B
decreases

C
remains the same

D
varies in a way that depends on the actual value of A

Solution