Structure of the Atoms Test

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Structure of the Atoms Test - 49

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Weekly Quiz Competition

Question 1
1 / -0

Rutherford's experiment on scattering of particles showed for the first time that the atom has:

A
electrons

B
protons

C
nucleus

D
neutrons

Solution

Rutherford's alpha-particle scattering experiment showed for the first time that an atom has a nucleus. He observed that some particles were being deflected, which indicated that the positive charges are confined to a small space in the atom. This positively charged portion of the atom is nucleus.
Question 2
1 / -0

Atoms have void spaces. It was first suggest by

A
Rutherford

B
Thomson

C
Lenard

D
Dalton
Question 3
1 / -0

The nucleus of an element contain 9 protons. Its valency would be.

A
1

B
3

C
2

D
5

Solution

As nucleus of the element contains nine protons, its atomic number is 9. Hence, the electronic configuration of the element is $$2,7$$. It needs one more electron to attain the stable inert gas configuration. Hence, its valency is 1.
Therefore, option $$A$$ is correct.
Question 4
1 / -0

Which of the following is not a correct statement according to Rutherford's atomic model?

A
$$99\%$$ of mass of an atom is centered in the nucleus.

B
Most of the part inside the atom is empty.

C
The size of nucleus is very small in comparison to the atom.

D
Electrons revolve around the nucleus in a fixed circular path.

Solution

Based on his experiment, Rutherford put forward the nuclear model of an atom, which had the following features:
(i) There is a positively charged centre in an atom called the nucleus. Nearly all the mass of an atom resides in the nucleus.
(ii) The electrons revolve around the nucleus in circular paths.
(iii) The size of the nucleus is very small as compared to the size of the atom.
Question 5
1 / -0

The radius of the first Bohr orbit of hydrogen atom is $$r$$. The radius of the $$3^{rd}$$orbit would be:

A
$$3r$$

B
$$9r$$

C
$$27r$$

D
$$none\ of\ these$$

Solution

$$r_n =r_0 \dfrac {n^2}{Z}\Rightarrow r_3 =r(3)^2 =9r \left(A / q, \dfrac {r_0}{Z}=r \right)$$

Option B is correct.
Question 6
1 / -0

The expression for Bohr's radius of an atom is

A
$$r = \dfrac{n^2h^2}{4\pi^2me^4z^2}$$

B
$$r = \dfrac{n^2h^2}{4\pi^2me^2z}$$

C
$$r = \dfrac{n^2h^2}{4\pi^2me^2z^2}$$

D
$$r = \dfrac{n^2h^2}{4\pi^2m^2e^2z^2}$$

Solution

$$ r = \dfrac{n^{2}h^{2}}{4\pi^{2} e^{2}mZ} $$

Hence, option B is correct.
Question 7
1 / -0

The ratio of the radii of the first three Bohr orbits is:

A
$$1:5:33$$

B
$$1:2:3$$

C
$$1:4:9$$

D
$$1:8:27$$

Solution

$$r_n \propto n^2$$

Option C is correct.
Question 8
1 / -0

Neutron is a fundamental particle carrying:

A
A charge of $$+1$$ unit and a mass of unit

B
No charge and a mass of $$1$$ unit

C
No charge and no mass

D
A charge of $$-1$$ and a mass of $$1$$ unit

Solution

Proton and $$e^{\ominus} $$ which are electrically charged, neutrons have no charge they are electrically neutral. The mass of a neutron is slightly greater than the mass of a proton, which is 1 atomic mass unit (amu). (An atomic mass unit equals about $$1.67 \times 10^{−27} Kgs$$.)
Option (B) is correct.
Question 9
1 / -0

Nucleons are:

A
Protons and electrons

B
Protons and neutrons

C
Electrons and neutrons

D
Electrons, protons and neutrons

Solution

Nucleon, either of the subatomic particles, proton(positively charged) and neutron(neutral), constituting atomic nuclei.
Hence, option $$B$$ is correct.
Question 10
1 / -0

The introduction of a neutron into the nuclear composition of an atom would lead to a change in:

A
The number of the electrons also

B
The chemical nature of the atom

C
Its atomic number

D
Its atomic weight

Solution

The number of protons represents the atomic number of an element.
The total number of protons and neutrons in an atom represents the mass number (atomic weight) of that element. So, the introduction of a neutron to an atom leads to an increase in mass number by one unit.

Hence, option $$D$$ is correct.

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Structure of the Atoms Test - 49

Result

Structure of the Atoms Test - 49

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Question 1

electrons

protons

nucleus

neutrons

Solution

Question 2

Rutherford

Thomson

Lenard

Dalton

Question 3

1

3

2

5

Solution

Question 4

$$99\%$$ of mass of an atom is centered in the nucleus.

Most of the part inside the atom is empty.

The size of nucleus is very small in comparison to the atom.

Electrons revolve around the nucleus in a fixed circular path.

Solution

Question 5

$$3r$$

$$9r$$

$$27r$$

$$none\ of\ these$$

Solution

Question 6

$$r = \dfrac{n^2h^2}{4\pi^2me^4z^2}$$

$$r = \dfrac{n^2h^2}{4\pi^2me^2z}$$

$$r = \dfrac{n^2h^2}{4\pi^2me^2z^2}$$

$$r = \dfrac{n^2h^2}{4\pi^2m^2e^2z^2}$$

Solution

Question 7

$$1:5:33$$

$$1:2:3$$

$$1:4:9$$

$$1:8:27$$

Solution

Question 8

A charge of $$+1$$ unit and a mass of unit

No charge and a mass of $$1$$ unit

No charge and no mass

A charge of $$-1$$ and a mass of $$1$$ unit

Solution

Question 9

Protons and electrons

Protons and neutrons

Electrons and neutrons

Electrons, protons and neutrons

Solution

Question 10

The number of the electrons also

The chemical nature of the atom

Its atomic number

Its atomic weight

Solution

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