Atoms Test

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Atoms Test - 39

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Weekly Quiz Competition

Question 1
1 / -0

Which state of triply ionised Beryllium $$(Be^{+++})$$ has the same orbital radius as that of the ground state of hydrogen ?

A
$$n = 3$$

B
$$n = 4$$

C
$$n = 1$$

D
$$n = 2$$

Solution

From Bohr's atomic model, atomic radius for $$n$$th state is given by the formula,
$$r=0.059\dfrac { { n }^{ 2 } }{ z } A$$

Since for Be, $$z=4$$

$$\dfrac { { n }^{ 2 } }{ 4 } =\dfrac { { 1 }^{ 2 } }{ 1 } $$

Hence, $$n=2$$
Question 2
1 / -0

If elements with principal quantum number $$n>4$$ were not allowed in nature, the number of possible elements would have been:

A
$$32$$

B
$$60$$

C
$$64$$

D
$$4$$

Solution

Hint:
Add all the elements from $$n=1$$ to $$n=4$$.

Step 1: Write the number of elements for each shell.
The number of elements for $$n=1$$ are $$2$$.
The number of elements for $$n=2$$ are $$8$$.
The number of elements for $$n=3$$ are $$18$$.
The number of elements for $$n=4$$ are $$32$$.

Step 2: adding all the elements,
from $$n=1$$ to $$n=4$$.
Total number $$= 2+8+18+32=60$$

$$\textbf{Hence option B correct}$$
Question 3
1 / -0

Which of the following is true regarding atoms according to Rutherford's gold foil experiment?

A
Are mostly space

B
Are in continuous motion

C
Have negative orbitals

D
Have diffuse charge distribution

E
Have dense crystalline structure

Solution

In Rutherford's experiment most of the $$\alpha$$ -particles were found passing the foil without any deflection which means atoms have a lot of empty space.
Question 4
1 / -0

The carrier of electromagnetic interaction is:

A
gluon

B
photon

C
meson

D
graviton

Solution

The carrier particle of the electromagnetic interaction is the Photon.
Photons of different energies span carries the electromagnetic spectrum of x rays, visible light, radio waves, and so forth.
Photons have zero mass and travels at the speed of light.
Question 5
1 / -0

The difference between the wavelengths of the Stokes line and Anti-Stokes lines in the Raman spectrum of $$H-Br$$ molecule is $$100\mathring { A } $$. If the wavelength of the Anti-Stokes line is $$5000\mathring { A } $$ the wavelength of the incident radiation is:

A
$$5050 \mathring { A } $$

B
$$4950 \mathring { A } $$

C
$$5100 \mathring { A } $$

D
$$4900 \mathring { A } $$

Solution

Stokes and antistokes lines are symmetrically placed about main line.
Therefore if the difference between the wavelengths of a stokes line and its corresponding antistokes lines is $$100 \mathring { A } $$, then the difference between antistokes line and main line is $$50 \mathring { A } $$.
More over wavelength of antistokes line is less than main line.
$$\therefore$$ wavelength of incident radiation is $$5050 \ \mathring { A } $$.
Question 6
1 / -0

Bohr's atom model assumes.

A
The nucleus is of infinite mass and is at rest

B
Electrons in a quantized orbit will not radiate energy

C
Mass of electron remains constant

D
All the above.
Solution
In 1913, Niels Bohr proposed a model for the hydrogen atom . The Bohr model was based on the following assumptions.
The electron in a hydrogen atom travels around the nucleus in a circular orbit.
The nucleus is of infinite mass and is rest.
Electrons in a quantized orbit will not radiate energy.
Mass of electron remains constant.
Question 7
1 / -0

Which of the following statement is true on a scattering of atom according to Rutherfords experiments on the alpha particle ?

A
Atoms are roughly spherical with a radius of about $${10}^{-10} m$$

B
The electrons occupy quantized energy levels, absorbing or emitting energy only when they make a quantum jump between these levels

C
The density of positive charge within an atom is not uniform throughout the atoms volume

D
Allowed electron orbits must have a circumference equal to a whole number times the electrons de Broglie wavelength

E
Alpha particles are positively charged

Solution

Rutherford's experiment found out that the density of positive charge was larger at the center of atom's volume from observation that the positively charge alpha particle scattered more when closer to the center of the atom, than when at the outer volume of atom. This suggested the presence of a positively charged center in the atom.
Question 8
1 / -0

The discrete spectral lines of line spectra occur when excitation of electrons takes place in

A
Solids

B
Liquids

C
Gases

D
Plastics

E
All of these

Solution

In solids atoms are not movable so the energy required to knock the electrons is same, but for liquids and gases, the atoms can move with some speed, thus the electrons that knock out may or may not go to the initial orbit. Thus, for solids discrete spectral lines are observed.
Question 9
1 / -0

Which of the following assumptions made by Neils Bohr regarding the hydrogen atom was NOT new and "radical"?

A
Electrons are only stable in certain orbits

B
Atoms only emit electromagnetic radiation when electrons transition to lower energy states

C
The Coulomb force is responsible for keeping the electron in orbit around the positive nucleus

D
An electron in a hydrogen atom can only orbit the nucleus if its angular momentum is some integer multiple of $$h/2 \pi$$

E
All of the above were new and "radical"

Solution

It is the electromagnetic force, one of the four fundamental forces of nature, theta governs the interaction of electrons with the positively charged nucleus to form an individual atom. The EM force is carried by photons, which serve in the capacity of gauge bosons as they do this force interaction.
Question 10
1 / -0

For absorption and emission spectra of atoms which one of the following particle changes energy levels?

A
Alpha

B
Electron

C
Neutron

D
Photon

E
Proton

Solution

Electrons are presents in different energy levels of the atoms. These electrons from lower energy levels jump to the higher energy levels during absorption spectra whereas transition of electrons from higher energy level to lower energy level takes place in emission spectra via emitting a photon.

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Atoms Test - 39

Result

Atoms Test - 39

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SHARING IS CARING

Question 1

$$n = 3$$

$$n = 4$$

$$n = 1$$

$$n = 2$$

Solution

Question 2

$$32$$

$$60$$

$$64$$

$$4$$

Solution

Question 3

Are mostly space

Are in continuous motion

Have negative orbitals

Have diffuse charge distribution

Have dense crystalline structure

Solution

Question 4

gluon

photon

meson

graviton

Solution

Question 5

$$5050 \mathring { A } $$

$$4950 \mathring { A } $$

$$5100 \mathring { A } $$

$$4900 \mathring { A } $$

Solution

Question 6

The nucleus is of infinite mass and is at rest

Electrons in a quantized orbit will not radiate energy

Mass of electron remains constant

All the above.

Solution

Question 7

Atoms are roughly spherical with a radius of about $${10}^{-10} m$$

The electrons occupy quantized energy levels, absorbing or emitting energy only when they make a quantum jump between these levels

The density of positive charge within an atom is not uniform throughout the atoms volume

Allowed electron orbits must have a circumference equal to a whole number times the electrons de Broglie wavelength

Alpha particles are positively charged

Solution

Question 8

Solids

Liquids

Gases

Plastics

All of these

Solution

Question 9

Electrons are only stable in certain orbits

Atoms only emit electromagnetic radiation when electrons transition to lower energy states

The Coulomb force is responsible for keeping the electron in orbit around the positive nucleus

An electron in a hydrogen atom can only orbit the nucleus if its angular momentum is some integer multiple of $$h/2 \pi$$

All of the above were new and "radical"

Solution

Question 10

Alpha

Electron

Neutron

Photon

Proton

Solution

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