CAIE IGCSE Chemistry Lithium Sodium and Potassium Trends

Cambridge IGCSE Chemistry 0620 syllabus for exams in 2026, 2027 and 20282026–2028

Practise comparing lithium, sodium and potassium and applying down-group trends in softness, density, melting point and water reactivity.

How this is tested

describe lithium, sodium and potassium as soft metals stored under oil to exclude air and water
apply decreasing melting point and generally increasing density down Group I
order reactivity as increasing down the group and compare vigour with cold water

[Maximum number: 1]

Lithium and potassium are metals in Group I of the Periodic Table.
Lithium has a melting point of $181^{\circ} \mathrm{C}$ and a density of $0.53 \mathrm{~g} / \mathrm{cm}^{3}$ .
Which row describes the melting point and density of potassium?

melting point in ${ }^{\circ} \mathrm{C}$

density in $\mathrm{g} / \mathrm{cm}^{3}$

less than 181

less than 0.53

less than 181

greater than 0.53

greater than 181

less than 0.53

greater than 181

greater than 0.53

How this is tested

Question 21