May/June 2026 Paper 42

Chromium, copper and nickel are transition elements. State two physical properties of transition elements that are different from Group I metals.

Write the formulas of the following compounds of transition elements.

Two ions that contain chromium are chromate(VI) ions, CrO${}_4^{2-}$, and dichromate(VI) ions, Cr${}_2$O${}_7^{2-}$. H${}^{+}$(aq) ions convert CrO${}_4^{2-}$(aq) ions to Cr${}_2$O${}_7^{2-}$(aq) ions. An equilibrium is reached.

Explain why this is not a redox reaction.

Describe this equilibrium in terms of: • the rate of the forward reaction and the rate of the reverse reaction • the concentration of the reactants and of the products.

Explain why increasing the pressure has no effect on the position of equilibrium.

Explain why adding an alkali moves the position of equilibrium to the left.

Transition elements form alloys. Name the alloy which is made by mixing copper with zinc.

Mixing chromium and nickel with iron and a non‑metallic element makes a type of steel. Name this type of steel and the non‑metallic element used.