chemistry MCQs - 9th class Chapter 02 Mcqs

1

Who proposed in 1803 that atoms are indivisible particles?

A

J.J. Thomson

B

John Dalton

C

Rutherford

D

Goldstein

2

Cathode rays were discovered during experiments with a...?

A

Gold foil

B

Cloud chamber

C

Discharge tube

D

Spectrometer

3

Which particle is approximately 1836 times heavier than an electron?

A

Neutron

B

Proton

C

Nucleus

D

Alpha particle

4

The charge on a cathode ray particle (electron) is...?

A

Positive

B

Neutral

C

Negative

D

Variable

5

Who discovered the proton?

A

J.J. Thomson

B

Chadwick

C

Rutherford

D

E. Goldstein

6

Canal rays are streams of...?

A

Electrons

B

Positively charged ions

C

Neutrons

D

Photons

7

Which fundamental particle has no charge?

A

Electron

B

Proton

C

Neutron

D

Ion

8

According to Rutherford's model, the central part of an atom is called the...?

A

Orbit

B

Shell

C

Nucleus

D

Electron cloud

9

Protons and neutrons within the nucleus are held together by...?

A

Gravitational force

B

Electrostatic force

C

Weak nuclear force

D

Strong nuclear force

10

The path of an electron in an atom is best described as...?

A

A fixed circular orbit

B

A fixed elliptical orbit

C

A probabilistic path

D

A straight line

11

The first shell or K shell can accommodate a maximum of how many electrons?

A

8

B

2

C

18

D

32

12

The formula to calculate the maximum number of electrons in a shell is...?

A

n^2

B

2n

C

2n^2

D

n+1

13

Which sub-shell is present in the first energy level (n=1)?

A

p sub-shell

B

s sub-shell

C

d sub-shell

D

f sub-shell

14

The third shell (n=3) consists of which sub-shells?

A

s, p

B

s, p, d, f

C

s, p, d

D

s only

15

The atomic number (Z) of an element represents the number of...?

A

Neutrons

B

Electrons in the outer shell

C

Protons

D

Protons and neutrons

16

The mass number (A) of an element is the sum of...?

A

Electrons and protons

B

Protons and neutrons

C

Electrons and neutrons

D

Only neutrons

17

How can the number of neutrons (N) in an atom be calculated?

A

N = A + Z

B

N = Z - A

C

N = A - Z

D

N = A

18

An atom of Carbon-12 (^12_6C) contains how many protons?

A

12

B

18

C

6

D

0

19

An atom of Uranium-238 (^238_92U) contains how many neutrons?

A

92

B

238

C

330

D

146

20

Atoms of the same element with the same number of protons but different numbers of neutrons are called...?

A

Ions

B

Molecules

C

Isomers

D

Isotopes

21

Which isotope of hydrogen does not contain a neutron?

A

Deuterium (^2H)

B

Tritium (^3H)

C

Protium (^1H)

D

Hydrogen-4

22

Isotopes of an element have different...?

A

Chemical properties

B

Atomic numbers

C

Number of protons

D

Physical properties

23

The process where an unstable nucleus emits radiation is called...?

A

Ionization

B

Radioactive decay

C

Nuclear fusion

D

Chemical reaction

24

Technetium-99m is a radioactive isotope used for...?

A

Carbon dating

B

Generating nuclear power

C

Medical diagnostic imaging

D

Testing metal strength

25

Radiocarbon dating uses the radioactive isotope...?

A

Uranium-238

B

Tritium

C

Carbon-14

D

Krypton-85

26

The mass of an atom is primarily concentrated in its...?

A

Electrons

B

Outermost shell

C

Nucleus

D

Sub-shells

27

The particles discovered by Goldstein in a discharge tube with a perforated cathode were called...?

A

Cathode rays

B

X-rays

C

Canal rays

D

Beta particles

28

The mass of a neutron is almost the same as the mass of a...?

A

Electron

B

Proton

C

Helium nucleus

D

Two electrons

29

In a neutral atom, the number of electrons is equal to the number of...?

A

Neutrons

B

Mass number

C

Protons

D

Shells

30

The symbol for the mass number is...?

A

N

B

Z

C

M

D

A

31

What is the relative mass of an electron?

A

~1 amu

B

~1836 amu

C

Very small, almost negligible

D

Equal to a proton

32

How many electrons can the 'p' sub-shell accommodate at most?

A

2

B

10

C

6

D

14

33

Elements in the periodic table are arranged according to their...?

A

Mass number

B

Number of neutrons

C

Atomic number

D

Number of isotopes

34

The relative atomic mass scale is based on which isotope?

A

Hydrogen-1

B

Oxygen-16

C

Carbon-12

D

Uranium-235

35

An atom that loses an electron becomes a...?

A

Anion (negative ion)

B

Cation (positive ion)

C

A different element

D

An isotope

36

What is the charge of a proton in Coulombs?

A

-1.6022 x 10^-19 C

B

+1.6022 x 10^-19 C

C

0.0

D

9.109 x 10^-31 C

37

What is the mass of a proton in Kg?

A

9.109 x 10^-31 Kg

B

1.675 x 10^-27 Kg

C

1.673 x 10^-27 Kg

D

1.6022 x 10^-19 Kg

38

Which shell has a higher energy level?

A

K shell

B

L shell

C

The one closer to the nucleus

D

All shells have equal energy

39

The isotope Tritium (^3H) is...?

A

Stable

B

Non-existent

C

Radioactive

D

An ion

40

The process of removing an electron from an atom is called...?

A

Decay

B

Reduction

C

Ionization

D

Fusion

41

Who conducted the gold foil experiment to discover the nucleus?

A

Dalton

B

Thomson

C

Rutherford

D

Goldstein

42

The 'd' sub-shell can hold a maximum of how many electrons?

A

2

B

6

C

10

D

14

43

Which of these is an application of radioactive isotopes?

A

Creating alloys

B

Purifying water

C

Diagnosing thyroid disorders

D

Manufacturing plastics

44

An oxygen atom with 8 protons and 8 neutrons would be symbolized as...?

A

16O

B

8O

C

24O

D

16/8O

45

The L-shell corresponds to which principal quantum number 'n'?

A

n=1

B

n=2

C

n=3

D

n=4

46

The positive ions produced in a discharge tube that travel towards the cathode are known as...?

A

Cathode rays

B

Electrons

C

Anode rays

D

Neutrons

47

According to the uncertainty principle, for an electron, we cannot precisely know both its...?

A

Mass and charge

B

Path and location

C

Speed and mass

D

Energy and spin

48

Which element's isotope is the standard for relative atomic mass?

A

Hydrogen

B

Helium

C

Oxygen

D

Carbon

49

Which statement about isotopes is true?

A

They have different numbers of electrons.

B

They have different chemical behaviors.

C

They have the same number of protons.

D

They have the same mass number.