Atoms Test

Result

Atoms Test - 44

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

Given mass number of gold = 197,
Density of gold = 19.7 g/cm$$^3$$
Avogadro's number = $$6 \times 10^{23} $$. The radius of the gold atom is approximately

A
$$1.5 \times 10^{-8} m$$

B
$$1.7 \times 10^{-9} m$$

C
$$1.5 \times 10^{-10} m$$

D
$$1.5 \times 10^{-12} m$$

Solution

Volume occupied by one gram atom of gold $$=\dfrac{m}{\rho}= \dfrac{197 g}{19.7 g/cm^3} = 10 cm^3$$
Volume of one atom $$=\dfrac{10}{N_A}= \dfrac{10}{6 \times 10^{-23}}$$ $$= \dfrac{5}{3} \times 10^{23} cm^3$$
Let $$r$$ be the radius of the atom.
$$\therefore \ \dfrac{4}{3} \pi r^3 = \dfrac{5}{3} \times 10^{23}$$
$$r^3 = \dfrac{50 \times 10^{-24}}{4 \times 3.14}$$
$$r = 1.5 \times 10^{-10} m$$
Question 2
1 / -0

In an electron gun, the control grid is given negative potential, relative to cathode in order to.

A
accelerate the electrons

B
decrease KE of electrons

C
repel the electrons

D
decelerate the electrons

Solution

In an electron gun, the control grid is given a negative potential relative to cathode in order to repel the electrons so that a converging beam of electrons emerges from gun.
Question 3
1 / -0

The ratio of the wavelength for $$2\rightarrow 1$$ transition in $${ Li }^{ + },{ He }^{ + }$$ and $$H$$ is :

A
$$1:2:3$$

B
$$1:4:9$$

C
$$4:9:36$$

D
$$3:2:1$$

Solution

Using $$\cfrac { 1 }{ \lambda } =R{ Z }^{ 2 }\left( \cfrac { 1 }{ { n }_{ 1 }^{ 2 } } -\cfrac { 1 }{ { n }_{ 2 }^{ 2 } } \right) \Rightarrow \lambda \propto \cfrac { 1 }{ { Z }^{ 2 } } $$
$$\Rightarrow { \lambda }_{ Li }:{ \lambda }_{ He }:{ \lambda }_{ H }=\cfrac { 1 }{ 9 } :\cfrac { 1 }{ 4 } :\cfrac { 1 }{ 1 } =4:9:36$$
Question 4
1 / -0

Which of the following is true?

A
Lyman series is a continuous spectrum

B
Paschen series is a line spectrum in the infrared

C
Balmer series is a line spectrum in the ultraviolet

D
The spectral series formula can be derived from the Rutherford model of the hydrogen atom

Solution

Lyman series lies in the ultraviolet region, Balmer series lies in the visible region and Paschen series onwards lie in the infrared region.
Question 5
1 / -0

The ratio of kinetic energy and the total energy of the electron in the nth quantum state of Bohr's atomic model of hydrogen atom is

A
$$-2$$

B
$$-1$$

C
$$+2$$

D
$$+1$$

Solution

The kinetic energy of the electron in the nth state
$$K=\dfrac {mZ^2e^4}{8\varepsilon ^2_0h^2n^2}$$
The total energy of the electron in the nth state
$$T=\dfrac {-mZ^2e^4}{8\varepsilon ^2_0h^2n^2}$$
$$\therefore \dfrac {K}{T}=-1$$
Question 6
1 / -0

If the atom $$^{257}_{100}{Fm}$$ follows the Bohr model and the radius of $$^{257}_{100}{Fm}$$ is n times the Bohr radius, then the value of n is :

A
4

B
$$\dfrac{1}{4}$$

C
200

D
100

Solution

According to Bohr's model
$$r_m=\dfrac{m^2}{2}.r_0$$
where, m is orbit number and $$r_0$$ is the Bohr's radius for $$^{257}_{100}{FM}$$,
$$Z=100, m=5, r_m=nr_0$$
$$nr_0=\dfrac{5^2r_0}{100}$$ or $$n=\dfrac{1}{4}$$
Question 7
1 / -0

The photoelectric effect represent that

A
Light has a particle nature

B
Electron has a wave nature

C
Proton has a wave nature

D
None of the above

Solution

According to Einstein's quantum theory, light propagates in the form of bundles (packets or quanta) of energy, each bundle is called a photon. The photoelectric effect represents that light has a particle nature.
Question 8
1 / -0

The ratio of areas of the electron orbits for the first excited state and the ground state for the hydrogen atom is

A
4 : 1

B
16 : 1

C
8 : 1

D
2 : 1

Solution
Question 9
1 / -0

If the series limit of Lymen series for hydrogen atom is equal to the series limit of Balmer series for a hydrogen like atom, then atomic number of this hydrogen like atom is

A
$$1$$

B
$$2$$

C
$$3$$

D
$$4$$

Solution

By using, $$\dfrac {1}{\lambda} = RZ^{2} \left [\dfrac {1}{n_{1}^{2}} - \dfrac {1}{n_{2}^{2}}\right ]$$
For hydrogen atom $$\dfrac {1}{(\lambda_{min})_{H}} = R\left [\dfrac {1}{1^{2}} - \dfrac {1}{\alpha}\right ] = R$$
$$\dfrac {1}{(\lambda_{min})_{H}} = R$$ or $$(\lambda_{min})_{H} = \dfrac {1}{R} .... (i)$$
For another atom
$$\dfrac {1}{(\lambda_{min})_{atom}} = RZ^{2} \left (\dfrac {1}{2^{2}} - \dfrac {1}{\alpha}\right ) = \dfrac {RZ^{2}}{4}$$
$$\dfrac {1}{(\lambda_{min})_{atom}} = \dfrac {4}{RZ^{2}} .... (ii)$$
From Eqs. (i) and (ii), we get
$$\dfrac {1}{R} = \dfrac {4}{RZ^{2}} = Z = 2$$.
Question 10
1 / -0

The adjoining diagram shows the energy levels for an electron in a certain, which transition shown represents the emission of a photon with the maximum energy

A
I

B
II

C
III

D
IV

Solution

Energy released during emission of photon is maximum for transition III.
Energy of photon, $$E={ E }_{ 2 }-{ E }_{ 1 }=\left( -\cfrac { { E }_{ 1 } }{ { (2) }^{ 2 } } \right) -(-{ E }_{ 1 })=\cfrac { 3{ E }_{ 1 } }{ 4 } $$

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Atoms Test - 44

Result

Atoms Test - 44

Score

-

Rank

-

SHARING IS CARING

Question 1

$$1.5 \times 10^{-8} m$$

$$1.7 \times 10^{-9} m$$

$$1.5 \times 10^{-10} m$$

$$1.5 \times 10^{-12} m$$

Solution

Question 2

accelerate the electrons

decrease KE of electrons

repel the electrons

decelerate the electrons

Solution

Question 3

$$1:2:3$$

$$1:4:9$$

$$4:9:36$$

$$3:2:1$$

Solution

Question 4

Lyman series is a continuous spectrum

Paschen series is a line spectrum in the infrared

Balmer series is a line spectrum in the ultraviolet

The spectral series formula can be derived from the Rutherford model of the hydrogen atom

Solution

Question 5

$$-2$$

$$-1$$

$$+2$$

$$+1$$

Solution

Question 6

4

$$\dfrac{1}{4}$$

200

100

Solution

Question 7

Light has a particle nature

Electron has a wave nature

Proton has a wave nature

None of the above

Solution

Question 8

4 : 1

16 : 1

8 : 1

2 : 1

Solution

Question 9

$$1$$

$$2$$

$$3$$

$$4$$

Solution

Question 10

I

II

III

IV

Solution

User

Question Analysis

My Perfomance

Score

-

Rank

-

Results Announcement on: coming Monday

Stay Tuned: We’ll update you on your result via email or SMS.