Atoms Test

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Atoms Test - 16

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Weekly Quiz Competition

Question 1
1 / -0

According to bohr model, the diameter of first orbit of hydrogen atom will approximately be

A
$$1$$$$A^{0}$$

B
$$0.529$$$$A^{0}$$

C
$$2.25$$$$A^{0}$$

D
$$0.725$$$$A^{0}$$

Solution

$$r=\dfrac{a_{0}n^{2}}{Z^2}$$
$$r=a_{0}(1)^{2}$$
$$=a_{0}$$
$$=0.53A^{0}$$

So, $$d=2\times r$$
$$=1\ A^{0}$$
Question 2
1 / -0

Radius of first Bohr orbit is $$\ r$$. The radius of 2nd Bohr orbit is

A
$$8\ r$$

B
$$2\ r$$

C
$$4\ r$$

D
$$\ 2\sqrt{2}r$$

Solution

$$\ r_{n}=n^{2}r$$ $$\ \therefore \ r_{2}= 4r$$
Question 3
1 / -0

The visible region of hydrogen spectrum was first studied by

A
Lyman

B
Balmer

C
Pfund

D
Brakett

Solution

When a hydrogen gas is heated or excited by electric means, the visible spectrum consists of lines these lines are shown here together with lines emitted by hot gases of Hg and He. These lines are called the Balmer Series, because Balmer saw some regularity in their wavelength, and he has given a formula to show the regularity.
Question 4
1 / -0

State the approximate voltage V$$_1$$ used to heat the filament in a cathode ray tube.

A
6 V

B
1 V

C
1000 V

D
6000 V

Solution

The tungsten filament heater, operated from a low voltage supply $$(about \ 6 V \ ac)$$ is surrounded by the metal cathode.
Question 5
1 / -0

The radius of the first Bohr orbit in hydrogen atom is $$r_0$$ then the radius of first orbit in helium atom will be

A
$$2r_0$$

B
$$4r_0$$

C
$$\displaystyle \frac {r_0}{2}$$

D
$$r_0$$

Solution

Radius of first orbit, $$r_n = k/Z$$ where $$k = 0.529$$ $$A^o$$
For Hydrogen atom, $$r_o = k/1 = k$$ $$(Z=1)$$
For Helium atom, $$r =k/2 $$ $$(Z=2)$$
$$\implies$$ $$r = \dfrac{r_o}{2}$$
Question 6
1 / -0

In which of the following systems will the radius of the first orbit $$(n=1)$$ be minimum?

A
Doubly ionized lithium

B
Singly ionized helium

C
Deuterium atom

D
Hydrogen atom

Solution

Radius $$r=0.529\dfrac{n^2}{Z}$$
So lithium has highest $$Z$$ among all, $$Z=3$$
So lithium doubly ionized will have the least radius.
Question 7
1 / -0

What is the purpose of filament in electron gun inside a cathode ray tube?

A
To support the cathode

B
To protect the cathode

C
To cool the cathode

D
To heat the cathode

Solution

When current passes through the filament it gets heated.
The heated filament transfers it's heat to the cathode plate.
Question 8
1 / -0

In a cathode ray tube, what is the effect on the beam of particles if it passes through the electric field?

A
the beam will get deflected towards the cathode

B
the beam will get deflected towards the anode

C
the beam will go undeflected.

D
None of the above

Solution

Beam deflects towards Positive Potential
Question 9
1 / -0

The purpose of cathode in cathode ray tube is ______

A
To emit the electrons

B
To absorb the electrons

C
To deflect the electrons

D
To emit the protons

Solution

The heated filament transfers its heat to the cathode the cathode coated by oxides of Barium or Strantium emit electrons on heating.
Question 10
1 / -0

Name a device which is commonly used to convert an electric signal into a visual signal

A
Cathode ray tube

B
Transducer

C
RMS converter

D
None of the above

Solution

Cathode-ray tubes that are used to convert electric signals into visible images may be divided into, for example, the following categories: television picture tubes, or kinescopes; cathode-ray oscillograph tubes; numerical indicator tubes; the indicator tubes used in radar sets

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Re-Attempt Weekly Quiz Competition

Atoms Test - 16

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Atoms Test - 16

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SHARING IS CARING

Question 1

$$1$$$$A^{0}$$

$$0.529$$$$A^{0}$$

$$2.25$$$$A^{0}$$

$$0.725$$$$A^{0}$$

Solution

Question 2

$$8\ r$$

$$2\ r$$

$$4\ r$$

$$\ 2\sqrt{2}r$$

Solution

Question 3

Lyman

Balmer

Pfund

Brakett

Solution

Question 4

6 V

1 V

1000 V

6000 V

Solution

Question 5

$$2r_0$$

$$4r_0$$

$$\displaystyle \frac {r_0}{2}$$

$$r_0$$

Solution

Question 6

Doubly ionized lithium

Singly ionized helium

Deuterium atom

Hydrogen atom

Solution

Question 7

To support the cathode

To protect the cathode

To cool the cathode

To heat the cathode

Solution

Question 8

the beam will get deflected towards the cathode

the beam will get deflected towards the anode

the beam will go undeflected.

None of the above

Solution

Question 9

To emit the electrons

To absorb the electrons

To deflect the electrons

To emit the protons

Solution

Question 10

Cathode ray tube

Transducer

RMS converter

None of the above

Solution

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