Chemistry 9701/21 — May/June 2020

Cambridge AS Level · AS Level Structured Questions · worked solutions for every part, with the mark scheme

questions

marks

minutes

Topics Atoms, Molecules and Stoichiometry · Chemical Bonding · Nitrogen and Sulfur · Hydrocarbons · Carboxylic Acids and Derivatives · Introduction to Organic Chemistry · +10 more

Q1Atomic StructureAtoms, Molecules and StoichiometryChemical BondingGroup IV (Group 14)Chemical PeriodicityFree sample

Gallium is a metal in Group 13 of the Periodic Table.

(a)

There are two stable isotopes of gallium, $^{69}\text{Ga}$ and $^{71}\text{Ga}$ .

(i)

State, with reference to subatomic particles, how the isotopes $^{69}\text{Ga}$ and $^{71}\text{Ga}$ differ from each other.

(ii)

State what further information is needed to calculate the relative atomic mass of gallium.

(b)

Gallium and its compounds show similar properties to aluminium and its compounds.

Gallium reacts with excess chlorine to form gallium trichloride.

(i)

At $500\text{ }^\circ\text{C}$ , gallium trichloride is a gas.

Suggest the type of attraction that exists at $500\text{ }^\circ\text{C}$ :

between atoms within a gallium trichloride molecule
between gallium trichloride molecules.

(ii)

When gallium trichloride is cooled a solid, $\text{Ga}_2\text{Cl}_6$ , forms.

Suggest the name of the attraction formed between two gallium trichloride molecules to form $\text{Ga}_2\text{Cl}_6$ .

(c)

Gallium metal reacts rapidly when exposed to air. A white solid layer is formed on its surface.

(i)

Suggest an equation to describe the reaction occurring when gallium metal is exposed to air.

(ii)

The table gives the formula of each gallium-containing product formed when gallium oxide reacts separately with hot aqueous hydrochloric acid and hot aqueous sodium hydroxide.

	formula of gallium-containing product
hot aqueous hydrochloric acid	$\text{GaCl}_3$
hot aqueous sodium hydroxide	$\text{NaGa(OH)}_4$

Give the name of the type of behaviour shown by gallium oxide in these reactions.

The rest of this paper

5 more questions

Q2Atoms, Molecules and Stoichiometry · Electrochemistry9M
Q3Chemical Energetics · Nitrogen and Sulfur · Reaction Kinetics13M
Q4Equilibria · Nitrogen and Sulfur · Chemical Bonding6M
Q5Hydrocarbons · Carboxylic Acids and Derivatives · Introduction to Organic Chemistry · Carbonyl Compounds · Halogen Compounds12M
Q6Introduction to Organic Chemistry · Hydrocarbons · Carbonyl Compounds · Analytical Techniques · Carboxylic Acids and Derivatives12M

Loading the full paper…