AS & A Level Chemistry - 9701 Paper 1 2021 Summer Zone 2

Which statement about the Avogadro constant is correct?

Which equation represents the first ionisation energy of iodine?

The structures represent three compounds, each with four carbon atoms per molecule.

Which row is correct?

The structural formula of alliin is shown.

What are the approximate bond angles \( x \), \( y \) and \( z \) in a molecule of alliin?

Flask Q contains 5 dm^3 of helium at 12 kPa pressure. Flask R contains 10 dm^3 of neon at 6 kPa pressure.
If the flasks are connected at constant temperature, what is the final pressure?

Sodium chloride, water and air represent three states of matter – solid, liquid and gas.
Which row is correct?
[Table_1]

The reaction pathway diagram for the catalysed reaction and the uncatalysed reaction between $N_2$ and $H_2$ is shown.

$$N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$$

Which letter represents the activation energy for the first step in the decomposition of $NH_3$ in the presence of a catalyst?

Nitrogen and oxygen can react together to form nitrogen monoxide, NO.
$$\text{N}_2 + \text{O}_2 \rightarrow 2\text{NO} \quad \Delta H = +180 \text{kJ mol}^{-1}$$
What is the bond energy of the bond between the atoms in NO?

The equation for a redox reaction is shown.

SnCl_2(aq) + 2HgCl_2(aq) \rightarrow SnCl_4(aq) + Hg_2Cl_2(s)

Which species is being oxidised in this reaction?

3.60 moles of hydrogen gas and 2.00 moles of iodine vapour are placed in a reaction vessel which is then sealed and maintained at a constant temperature.
The equation for the reaction is shown. $$ H_2 + I_2 \rightleftharpoons 2HI $$
At equilibrium, 3.20 moles of hydrogen remain. All reactants and products are gaseous.
What is the value of $K_p$ under these conditions?

Two chemicals, X and Y, react together in solution to give product Z.
The rate of formation of product Z at the start of the reaction was measured in five experiments, 1–5, using various concentrations of X and Y. The results are shown.

[Table_1]

Which statement is correct?

A sample of SiCl$_4$ is added to cold water.
Which statement describes the mixture formed at the end of the reaction?

L and M are elements in Period 3 of the Periodic Table.
• The oxide of L is a solid at room temperature. This oxide has a giant structure.
• The chloride of L does not react with water.
• Argon is the only element in Period 3 with a lower melting point than M.
Which formula represents a compound of elements L and M?

A farmer requires a solid compound to raise the pH of the soil in a field from 5.5 to above 6.0. Which compound could the farmer use?

Z is an anhydrous compound of a Group 2 element. When it is heated, Z undergoes thermal decomposition to produce two different gases. Z has relatively low thermal stability compared to other Group 2 compounds containing the same anion as Z. What is compound Z?

Which row gives mixtures that \textbf{both} result in the oxidation of a halide ion?

[Table_1]

Chlorine gas is widely used to treat contaminated water. When chlorine is added to water, which chemical species present is responsible for killing bacteria?

What is an environmental consequence of the uncontrolled use of nitrate fertilisers?

Ammonia gas, $\text{NH}_3$, and hydrogen sulfide gas, $\text{H}_2\text{S}$, react together to form the salt ammonium sulfide, $(\text{NH}_4)_2\text{S}$. Ammonium sulfide dissolves in water to produce an orange alkaline solution.
\[ (\text{NH}_4)_2\text{S(aq)} \rightleftharpoons \text{NH}_3\text{(aq)} + \text{NH}_4\text{SH(aq)} \]
The addition of NaOH(aq) to this solution produces a gas, X.
The addition of HCl(aq) to a separate portion of this solution produces a gas, Y.
X and Y could represent different gases or identical gases.
What are the identities of X and Y? [Table_1]

Compound P is treated with an excess of hydrogen gas in the presence of a nickel catalyst. The product Q is fully saturated.

What is the number of chiral carbon atoms in the product Q?

Hexadeca-10,12-dien-1-ol is produced by silk moths from hexadecanoic acid in a three-step enzymic process. Which row contains correct descriptions of the three steps?

Compound X can be converted into compound Y in a single step.

What could be the identity of X?

Methane and bromine react by free radical substitution.
P and Q are involved in the reaction mechanism.
P and Q:
• are both involved in propagation steps as reactants
• are both involved in termination steps as reactants.
What could be P and Q?

A few drops of 2-bromopropane were placed in a test-tube. An equal volume of aqueous silver nitrate was added. A precipitate was formed.
The experiment was repeated with 2-iodopropane.
Which row is correct?
[Table_1]

Sodium methoxide, Na⁺CH₃O⁻, reacts with 2-chloro-2-methylpropane in a nucleophilic substitution reaction. The nucleophile is the CH₃O⁻ ion.
Which row is correct?
[Table_1]

Alcohol X reacts with concentrated sulfuric acid to produce a mixture of products.
Two of the products are structural isomers of each other.
What could be X?

Which reaction will form a strong organic base?

Which reaction mechanism for the formation of $C_2H_5CH(OH)(CN)$ is correct?

The synthesis shown may be used for the production of propan-1-ol. Which row gives the correct reagents for steps 1 and 2? [Table_1]

The molecular formula of Z is $C_4H_8O$.
The infra-red spectrum of Z is shown.



What could be Z?

In which ions are the number of electrons equal to the number of neutrons?
1. $^{19}_{9}\text{F}^-$
2. $^{31}_{15}\text{P}^-$
3. $^{23}_{11}\text{Na}^+$

Compound X is a straight chain hydrocarbon with an $M_r$ of 84.
What can be determined about X?
1 empirical formula
2 molecular formula
3 whether X contains a C=C bond or not

When a sample of ammonium chloride is warmed it decomposes into ammonia and hydrogen chloride gas.
$$\text{NH}_4\text{Cl}(s) \rightarrow \text{NH}_3(g) + \text{HCl}(g) \space \text{reaction 1}$$

When the mixture of hot ammonia and hydrogen chloride gases hit a cold surface, a white solid of ammonium chloride reforms.
Which statements are correct?
1 Reaction 1 is in dynamic equilibrium.
2 Reaction 1 is reversible.
3 Reaction 1 is an endothermic reaction.

The responses A to D should be selected on the basis of
[Table_1]
No other combination of statements is used as a correct response.

Hydrogen chloride gas is formed by the reaction shown.
$$\text{H}_2(g) + \text{Cl}_2(g) \to 2\text{HCl}(g)$$
What will change the average kinetic energy of the reacting gas particles?
1. increasing the temperature and increasing the concentration of hydrogen
2. cooling the reaction mixture and adding a catalyst
3. adding a catalyst and increasing the concentration of chlorine

Which oxides will cause a change in pH when added to water?
1. CaO
2. \( \text{Al}_2\text{O}_3 \)
3. \( \text{SiO}_2 \)

Which reaction routes can be used to make a pure sample of barium sulfate?

1. \( \text{Ba} \xrightarrow{\text{heat in } O_2} \text{product} \xrightarrow{\text{dilute } HCl} \text{product} \xrightarrow{\text{dilute } H_2SO_4} \text{product} \xrightarrow{\text{filter, wash and dry}} \)
2. \( \text{Ba(NO}_3)_2 \xrightarrow{\text{strong heat in air}} \text{solid product} \xrightarrow{\text{an excess of water}} \text{product} \xrightarrow{\text{dilute } H_2SO_4} \text{product} \xrightarrow{\text{filter, wash and dry}} \)
3. \( \text{Ba(OH)}_2 \xrightarrow{\text{dilute } HNO_3} \text{product} \xrightarrow{\text{dilute } H_2SO_4} \xrightarrow{\text{filter, wash and dry}} \text{product} \)

Cortisone is a synthetic hormone.
[Image_1: Structure of cortisone]
Which classes of alcohol does this molecule contain?

Which changes are commonly involved in the formation of an addition polymer?
1. the formation of a $\sigma$-bond
2. the breaking of a $\pi$-bond
3. the change in hybridisation of the orbitals of a carbon atom from $sp^2$ to $sp^3$

Which alcohols can be oxidised to form an organic compound which will give coloured precipitates with both 2,4-dinitrophenylhydrazine reagent and alkaline aqueous iodine?
[Image_1: Structure of alcohols 1, 2, and 3]

Which mixtures form a carboxylic acid as one of the products?
[Image_1: Reaction Mixtures]