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CAIE A-Level Chemistry AS 1.2 Isotopes Questions

Practise defining isotopes and linking neutron-number differences to physical properties, abundance and relative atomic mass.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • define isotopes as atoms of the same element with equal proton number but different neutron numbers
  • explain identical chemical properties through the same electron configuration
  • use isotopic mass and percentage abundance to calculate or interpret relative atomic mass

Covered syllabus points

1.2.1—Terms: isotope1.2.2—The notation x1.2.3—Isotopes of the same element have the same1.2.4—Isotopes of the same element have different

Question 1

[Maximum number: 1]

The table shows the numbers of protons, neutrons and electrons in four different particles, W, X, Y, and Z.

Table for Question 1 — CAIE A-Level Chemistry AS

Which pair represents the atoms of two isotopes of the same element?

A

W and Y

B

W and Z

C

X and Y

D

X and Z

Question 2

[Maximum number: 1]

Which statements are correct when referring to the two common isotopes of chlorine?
1 The isotopes have different masses.
2 The isotopes have different numbers of nucleons.
3 The isotopes have the same chemical reactions.

A

1, 2 and 3 are correct

B

1 and 2 only are correct

C

2 and 3 only are correct

D

1 only is correct

Question 3

[Maximum number: 2]

Calcium, magnesium and radium are Group 2 elements. Radium follows the same trends as the other members of Group 2.

A sample of magnesium contains three isotopes, 25Mg,26Mg{ }^{25} \mathrm{Mg},{ }^{26} \mathrm{Mg} and X.

The percentage abundance of the three isotopes is shown in Table 1.1.

Table 1.1

Table 1.1

State one similarity and one difference in the properties of these isotopes of magnesium. Explain your answer.

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