MCQs — Atomic Structure

Practice questions for Chemistry.

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Question 81

The isotope of hydrogen with no neutrons, containing just one proton, is called:

A. Deuterium

B. Tritium

C. Protium

D. Helium

Question 82

The isotope of hydrogen with one proton and one neutron is called:

A. Protium

B. Deuterium

C. Tritium

D. Helium-3

Question 83

The isotope of hydrogen with one proton and two neutrons is called:

A. Protium

B. Deuterium

C. Tritium

D. Helium-4

Question 84

How do protium, deuterium and tritium differ from one another?

A. They differ in their number of protons

B. They all have one proton but differ in their number of neutrons (0, 1 and 2 respectively)

C. They are different elements entirely

D. They have no neutrons in common

Question 85

Water made using deuterium instead of ordinary hydrogen is commonly called:

A. Heavy water

B. Light water

C. Hard water

D. Soft water

Question 86

Why is heavy water denser than ordinary water?

A. Heavy water contains more oxygen atoms than ordinary water

B. Heavy water has fewer hydrogen atoms than ordinary water

C. Deuterium has more protons than ordinary hydrogen

D. Deuterium atoms are heavier than ordinary hydrogen atoms because they contain an extra neutron

Question 87

An isotope of hydrogen is found to contain one proton and one neutron in its nucleus. This isotope is:

A. Deuterium

B. Protium

C. Tritium

D. Helium

Question 88

The most abundant, stable isotope of carbon, with a mass number of 12, is called:

A. Carbon-13

B. Carbon-14

C. Carbon-16

D. Carbon-12

Question 89

The isotope of carbon with a mass number of 13, which is stable but less abundant than carbon-12, is called:

A. Carbon-12

B. Carbon-13

C. Carbon-14

D. Carbon-11

Question 90

The radioactive isotope of carbon, with a mass number of 14, used in dating ancient materials, is called:

A. Carbon-12

B. Carbon-13

C. Carbon-14

D. Carbon-16

Question 91

Why is carbon-12 far more abundant in nature than carbon-14?

A. Carbon-14 is the only isotope found in living things

B. Carbon-12 is a stable isotope, while carbon-14 is radioactive and continuously decays

C. Carbon-12 is radioactive, while carbon-14 is stable

D. Carbon-12 and carbon-14 are equally abundant

Question 92

Carbon-13 is often used in scientific research mainly as a:

A. Non-radioactive tracer to study chemical and biological processes

B. Fuel source for nuclear reactors

C. Material for building nuclear weapons

D. Standard for measuring temperature

Question 93

A fossil sample is analysed and found to contain a small amount of a radioactive carbon isotope with mass number 14. This isotope is most likely used to:

A. Determine the fossil's colour

B. Measure the fossil's density directly

C. Estimate the age of the fossil

D. Identify the fossil's chemical formula

Question 94

Isotopes of the same element have the same:

A. Mass number

B. Number of neutrons

C. Physical properties

D. Atomic number and number of protons

Question 95

An atom of hydrogen has one proton and no neutrons, while another atom of hydrogen has one proton and two neutrons. These two atoms are best described as:

A. Different elements

B. Ions of hydrogen

C. Isotopes of hydrogen

D. Isomers of hydrogen

Question 96

Why do isotopes of an element occupy the same position in the periodic table?

A. They have the same atomic number, which determines an element's position in the periodic table

B. They have the same mass number

C. They have completely different chemical properties

D. They belong to entirely different elements

Question 97

The number of neutrons in an atom of carbon-14 is:

A. 6

B. 8

C. 12

D. 14

Question 98

An atom of carbon-13 has how many neutrons?

A. 6

B. 13

C. 1

D. 7

Question 99

Isotopes are described as chemically similar but physically different mainly because chemical behaviour is determined by:

A. The number of neutrons

B. The number and arrangement of electrons

C. The mass number

D. The total mass of the atom

Question 100

If two isotopes of the same element have very different mass numbers, would you expect their chemical reactivity to be very different? Why or why not?

A. Yes, because heavier isotopes always react completely differently

B. Yes, because isotopes are actually different elements

C. No, because isotopes have no electrons at all

D. No, because their chemical reactivity depends mainly on their identical number of electrons, not their mass

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