Free Printable Physics Unit 10 Test

1.

The transition from state n = 3 to n =1 in a hydrogen like atom results in ultra violet radiation. Infrared radiation will be obtained in transition from

a)

$3\rightarrow2$

b)

$4\longrightarrow2$

c)

$4\longrightarrow3$

d)

$2\longrightarrow1$

2.

Two radioactive elements X and Y have half-lives of 50 and 100 minutes respectively. Initial sample of both the elements have same no of atoms. The ratio of the remaining number of atoms of X and Y after 200 minutes is

a)

2

b)

1/4

c)

4

d)

5/4

3.

When $P_{15}^{30}$ decays to become $Si_{14}^{30}$ which particle is released.

a)

Electron

b)

$\alpha$ -particle

c)

Neutron

d)

Positron

4.

With the increase in quantum number the energy difference between consecutive energy levels

a)

Remains constant

b)

Decreases

c)

Increases

d)

Sometimes increases sometimes decreases

5.

The Balmer series for hydrogen atom corresponds to electronic transitions that terminate in the state of quantum number n = 2. The longest wavelength of photon emitted is

a)

$\frac{5R}{36}$

b)

$\frac{36}{5R}$

c)

$\frac{36}{5}$

d)

$\frac{5}{36}$

6.

During the transition of Electron of Hydrogen atom from higher orbit to a third orbit, a photon of:

a)

Paschen series is emitted

b)

Lyman series is emitted

c)

Balmer series is emitted

d)

Brakett series is emitted

7.

An electron jumps from the 4th orbit to the 2nd orbit of hydrogen atom. Given the

Rydberg's constant R = 10 ⁵ cm ^-1 . The frequency in Hz of the emitted radiation will be

a)

$\frac{3}{16}\times10^5$

b)

$\frac{3}{16}\times10^{15}$

c)

$\frac{9}{16}\times10^{15}$

d)

$\frac{3}{4}\times10^{15}$

8.

The ratio of the frequencies of the long wavelength limits of Lyman and Balmer series of hydrogen spectrum is

a)

27 : 5

b)

5 : 27

c)

4 : 1

d)

1 : 4

9.

Which two nuclei contain the same number of neutrons?

a)

$_6^{12}C\ and\ _6^{14}C$

b)

$_{11}^{23}Na\ and\ _{12}^{24}Mg$

c)

$_7^{16}N\ and\ _8^{15}C$

d)

$_{14}^{32}Si\ and\ _{12}^{32}P$

10.

The relationship between decay constant $\lambda$ and half-life T_1/2 of the radioactive substance is

a)

$\lambda T_{\frac{1}{2}}=\ ℓn\left(2\right)$

b)

$\lambda T_{\frac{1}{2}}=\ ℓn\left(\frac{1}{2}\right)$

c)

$\frac{\lambda}{T_{\frac{1}{2}}}=ℓn\left(2\right)$

d)

$\lambda=\ ℓn\left(2\right)$

11.

The percentage of the original of a radioactive material left after five half-lives is approximately:

a)

1%

b)

3%

c)

5%

d)

20%

12.

Example of somatic effects are

a)

Skin burn

b)

Loss of hair

c)

Drop in the white blood cells

d)

All of these

13.

According to Bohr's theory the moment of momentum of an electron revolving in second orbit of hydrogen atom will be

a)

2πh

b)

h/π

c)

πh

d)

2h/π

14.

In Bohr's model of hydrogen atom, let PE represents potential energy and TE the total energy. In going to a higher level

a)

PE decreases, TE increases

b)

PE decreases, TE decreases

c)

PE increases, TE increases

d)

PE increases, TE decreases

15.

The half-life of a certain element is 3.5 days at S.T.P. If the temperature is doubled and pressure is reduced to half then half-life of the same element will be

a)

1.75 days

b)

7 days

c)

3.5 days

d)

14 days

16.

Due to emission of $\beta^+-rays$

a)

Mass of the Nucleus Increases

b)

Charge number Increases

c)

Mass of the Nucleus Decreases

d)

Charge number Decreases

17.

During radioactive series parent nucleus is $_{94}^{232}X$ and last daughter nucleus is $_{84}^{208}Y$ How many a and b-particles are emitted during this change

a)

$6\alpha,3\beta$

b)

$4\alpha,4\beta$

c)

$6\alpha,2\beta$

d)

$4\alpha,6\beta$

18.

The activity of radioactive sample:

a)

Is constant

b)

Decreases linearly with time

c)

Increases with time

d)

Decreases exponentially with time

19.

1 curie is equal to disintegrations per second

a)

3.7 × 10¹⁰

b)

3.7 × 10²⁰

c)

5.7 × 10¹⁰

d)

3.7 × 10¹³

20.

If 20 g of a radioactive substance reduces to 10 g in 4 minutes, then in what time will 80 g of the same substance reduce to 10 g?

a)

8 min

b)

12 min

c)

16 min

d)

20 min

21.

Which of the following is true for number of spectral lines in going from Lyman series to P fund series?

a)

Increases

b)

Unchanged

c)

Decreases

d)

May decreases or increases

22.

A certain radioactive nuclide of mass number ‘x’ decay by $\beta$ –emission and $\alpha$ – emission to a second nuclide of mass number ‘t’, which of the following correctly relates ‘x’ and ‘t’?

a)

x = t–4

b)

x + 3 =t

c)

x = t+4

d)

x –1 = t

23.

If a C-14 has a half-life of 5730 years, then how long will it take for quantity of C-14 in a sample to drop to 1/8 of initial quantity?

a)

2.58 × 10⁴ years

b)

1.44 × 10⁴ years

c)

1.72 × 10⁴ years

d)

2.58 × 10⁴ years

24.

The wavelength of last spectral line in Lyman series (in of Rydberg constant) is

a)

R

b)

R²

c)

$\frac{1}{R}$

d)

$\frac{1}{R^2}$

25.

What percentage of original radioactive atoms is left after four half-lives?

a)

0.3%

b)

6.25 %

c)

12.5 %

d)

3.125%

26.

The decay constant λ of the radioactive sample is the probability of decay of an atom in unit time, then

a)

λ decreases as atoms become older

b)

λ is independent of the age

c)

λ increases as the age of atoms increases

d)

Behaviour of λ with time depends on the nature of the activity

27.

The rate of decay of radioactive element at a given instant of time is 10³ disintegration/second. If the half-life of this element is 1 second, then the rate of decay after 3 second will be

a)

12 per sec

b)

500 per sec

c)

50 per sec

d)

125 per sec

28.

Number of spectral lines in hydrogen atom is

a)

3

b)

15

c)

6

d)

Infinite

29.

Which of the following transition will have highest emission wavelength?

a)

n=2 ton=1

b)

n=2 ton=5

c)

n=1 to n=2

d)

n=5 to n=2

30.

According to Bohr’s principle, what is the relation between the principal quantum number and the radius of the orbit?

a)

r proportional to 1/n

b)

r proportional to 1/n²

c)

r proportional to n

d)

r proportional to n²

31.

As per radioactive decay law, the small amount of disintegration of the isotope in a small period is equal to

a)

–λN

b)

λN

c)

–2λN

d)

2λN

32.

The decay constant of a radioactive element is 0.01 per second. Its half-life period is

a)

693 sec

b)

6.93 sec

c)

0.693 sec

d)

69.3 sec

33.

The equation of Rydberg constant is given by:

a)

$R_H=\frac{h_o}{m^o}$

b)

$R_H=\frac{E_o}{\lambda}$

c)

$R_H=\frac{E_o}{hc}$

d)

$R_H=\frac{1}{he}$

34.

Nucleus of an atom whose atomic mass is 24 consists of

a)

11 electrons, 11 protons and 13 neutrons

b)

11 protons and 13 neutrons

c)

11 electrons, 13 protons and 11 neutrons

d)

11 protons and 13 electrons

35.

Which of the following statements is not TRUE about α- radiation?

a)

A. It is produced by unstable nuclei

b)

It is a short wavelength electromagnetic photon

c)

It can penetrate a piece of paper

d)

It can be deflected by a magnetic field

36.

A radioactive material undergoes decay by ejecting electrons. The electron ejected in this process is

a)

The electron from the decay of a neutron

b)

The electron present in the nucleus

c)

The resulting from the conversion of photon

d)

An orbital electron

37.

A radioactive nucleus undergoes a series of decay according to the scheme $\alpha,\beta,\propto,\gamma$ $A\rightarrow A_1\rightarrow A_2\rightarrow A_3\rightarrow A_4$ .If the mass number and atomic number of A are 180 and 72 respectively, then what are these number for A₄

a)

172 and 69

b)

176 and 69

c)

174 and 70

d)

None of these

38.

The ratio between the first three orbits of hydrogen atom is

a)

1:2:3

b)

2:4:6

c)

1:4:9

d)

1:3:5

39.

Various types of cancer are treated by

a)

Cobalt-60

b)

Strontium-90

c)

Carbon-14

d)

Nickel-63

40.

Which of the following pairs is an isobar?

a)

$_1H^1\ and\ _1H^2$

b)

$_1H^2\ and\ _1H^3$

c)

$_6C^{12}\ and\ _6C^{13}$

d)

$_{15}P^{30}\ and\ _{14}Si^{30}$

Physics Unit 10 Test

Total questions: 40

Worksheet time: 3600secs

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