chemistry MCQs - 11th class Chapter 05 Mcqs

1

According to Dalton's theory, what were considered the ultimate, indivisible particles of matter?

A

Molecules

B

Atoms

C

Electrons

D

Compounds

2

Who is credited with the discovery of the electron?

A

Goldstein

B

Chadwick

C

Rutherford

D

J.J. Thomson

3

At what pressure inside the discharge tube does the original glow disappear and cathode rays are produced?

A

1 torr

B

0.1 torr

C

0.01 torr

D

10 torr

4

Which property of cathode rays suggests they are material particles with momentum?

A

They cast a shadow

B

They are deflected by electric fields

C

They can drive a small paddle wheel

D

They produce X-rays

5

The charge-to-mass (e/m) ratio of cathode rays is constant regardless of the?

A

Gas in the tube

B

Material of the cathode

C

Voltage applied

D

Both A and B

6

Who discovered positive rays (canal rays) in 1886?

A

J.J. Thomson

B

E. Goldstein

C

Rutherford

D

Stoney

7

The e/m value for positive rays is maximum when which gas is used in the discharge tube?

A

Helium

B

Neon

C

Oxygen

D

Hydrogen

8

The mass of a proton is how many times greater than the mass of an electron?

A

1840 times

B

1386 times

C

1836 times

D

1638 times

9

Who predicted the existence of a neutral particle in the atom in 1920?

A

Chadwick

B

Bohr

C

Rutherford

D

Moseley

10

James Chadwick discovered the neutron in 1932 by bombarding which element with alpha particles?

A

Polonium

B

Beryllium

C

Gold

D

Nitrogen

11

Slow neutrons are considered more effective for what purpose?

A

Ionization

B

Fission

C

Producing X-rays

D

Causing fluorescence

12

What is the value of the charge on an electron as determined by Millikan's oil drop experiment?

A

1.6022 x 10^-19 C

B

1.7588 x 10^11 C

C

9.1095 x 10^-31 C

D

6.02 x 10^23 C

13

In Rutherford's gold foil experiment, what did the backward deflection of a few alpha particles indicate?

A

The atom is mostly empty space

B

The presence of electrons

C

The presence of a small, dense, positively charged nucleus

D

The atom is electrically neutral

14

What was the main defect of Rutherford's atomic model?

A

It couldn't explain the nucleus

B

It couldn't explain the charge on the electron

C

It couldn't explain the stability of the atom

D

It couldn't explain the existence of protons

15

According to Planck's quantum theory, energy is emitted or absorbed in discrete units called?

A

Electrons

B

Photons

C

Protons

D

Quanta

16

The energy of a quantum of radiation is directly proportional to its?

A

Wavelength

B

Velocity

C

Frequency

D

Amplitude

17

In Bohr's model, what happens to energy when an electron jumps from a lower orbit to a higher orbit?

A

It is emitted

B

It is absorbed

C

It remains unchanged

D

It becomes zero

18

The angular momentum of an electron in a specific orbit, according to Bohr, is?

A

Quantized

B

Continuous

C

Always zero

D

Infinite

19

The radius of the first orbit (n=1) of a hydrogen atom is?

A

0.529 pm

B

0.529 nm

C

0.529 Å

D

2.11 Å

20

What happens to the distance between adjacent orbits as 'n' increases in a hydrogen atom?

A

It decreases

B

It stays the same

C

It increases

D

It becomes zero

21

The energy of an electron in an orbit has a negative sign because the electron is?

A

Moving very fast

B

Negatively charged

C

Bound to the nucleus

D

In a quantized state

22

The ionization energy of hydrogen is the energy difference between which two levels?

A

n=1 and n=2

B

n=2 and n=3

C

n=1 and n=∞

D

n=2 and n=∞

23

A spectrum consisting of a rainbow of colors without any dark spaces is called a?

A

Line spectrum

B

Atomic spectrum

C

Continuous spectrum

D

Absorption spectrum

24

Which spectral series for the hydrogen atom lies in the visible region?

A

Lyman series

B

Balmer series

C

Paschen series

D

Pfund series

25

The spectral lines of the Lyman series are produced when an electron jumps to which orbit?

A

n=1

B

n=2

C

n=3

D

n=4

26

Bohr's atomic model fails to explain the spectrum of which of the following?

A

H

B

He+

C

Li+2

D

He

27

The splitting of spectral lines in the presence of a strong magnetic field is known as the?

A

Stark effect

B

Compton effect

C

Photoelectric effect

D

Zeeman effect

28

X-rays are produced when fast-moving electrons strike a?

A

Gas molecule

B

Glass tube

C

Heavy metal anode

D

Fluorescent screen

29

Moseley's law established a linear relationship between the square root of the frequency of X-rays and the?

A

Atomic mass

B

Atomic number

C

Number of neutrons

D

Mass number

30

Who proposed the wave-particle duality of matter?

A

Planck

B

Einstein

C

de Broglie

D

Heisenberg

31

According to de Broglie's equation, the wavelength of a particle is inversely proportional to its?

A

Energy

B

Charge

C

Momentum

D

Frequency

32

The wave nature of electrons was experimentally verified by?

A

J.J. Thomson

B

Rutherford

C

Davisson and Germer

D

Millikan

33

Heisenberg's Uncertainty Principle states that it is impossible to simultaneously measure the exact position and ______ of an electron.

A

Charge

B

Mass

C

Spin

D

Momentum

34

The volume of space where there is a 95% probability of finding an electron is called an?

A

Orbit

B

Shell

C

Nodal plane

D

Atomic orbital

35

Which quantum number determines the energy level or shell of an electron?

A

Principal (n)

B

Azimuthal (l)

C

Magnetic (m)

D

Spin (s)

36

The shape of an orbital is determined by which quantum number?

A

Principal (n)

B

Azimuthal (l)

C

Magnetic (m)

D

Spin (s)

37

An orbital with l=1 is designated as which type of subshell?

A

s

B

p

C

d

D

f

38

What is the shape of an s-orbital?

A

Dumb-bell

B

Spherical

C

Double dumb-bell

D

Complex

39

How many degenerate orbitals are there in a p-subshell?

A

1

B

3

C

5

D

7

40

The magnetic quantum number (m) specifies the orbital's?

A

Size

B

Shape

C

Energy

D

Orientation in space

41

The spin quantum number (s) was introduced to explain which phenomenon?

A

Zeeman effect

B

Stark effect

C

Doublet line structure

D

Fine structure

42

What is the maximum number of electrons that can be accommodated in a shell with n=3?

A

8

B

10

C

18

D

32

43

Which principle states that electrons are filled in subshells in order of increasing energy?

A

Hund's Rule

B

Pauli Exclusion Principle

C

Aufbau Principle

D

(n+l) rule

44

Pauli's Exclusion Principle implies that two electrons in the same orbital must have?

A

The same spin

B

Opposite spins

C

The same charge

D

Different energy

45

According to Hund's rule, when filling degenerate orbitals, electrons should be placed in separate orbitals with ______ spin first.

A

opposite

B

paired

C

no

D

the same

46

If two subshells have the same (n+l) value, which one is filled first?

A

The one with the higher n value

B

The one with the lower n value

C

The one with the higher l value

D

The one with the lower l value

47

The electronic configuration of Chromium (Z=24) is an exception, having the configuration?

A

[Ar] 4s²3d⁴

B

[Ar] 4s¹3d⁵

C

[Ar] 4s²3p⁶3d²

D

[Ar] 4s¹3p⁶3d³

48

The region between two orbitals where the probability of finding an electron is zero is called a?

A

Shell

B

Subshell

C

Nodal plane

D

Electron cloud

49

The mass of a neutron is approximately?

A

Equal to an electron

B

Slightly less than a proton

C

Equal to a proton

D

Slightly more than a proton