2023 A Level H2 Chemistry Paper 1 Solutions - Questions 1 to 10

Question 1

Answer: B

Topic: Atomic Structure

Explanation:

Lanthanoids neodymium, Nd, has 60 protons while promethium, Pm, has 61 protons.

We can determine Nd²⁺ has 85 neutrons and 58 electrons while Pm³⁺ has 84 neutrons and 58 electrons.

Hence Nd²⁺ has more neutrons and both ions have the same number of electrons.

Question 2

Answer: C

Topic: Chemical Bonding

Explanation:

The bigger the difference in electronegativity between 2 atoms in a bond, the stronger the ionic character.

Hence YCl has greater ionic character than ZO2 since Y-Cl bond has a greater difference in electronegativity than Z-O bond.

Question 3

Answer: C

Topic: Chemical Bonding

Explanation:

Bromine atom has more electrons than chlorine atom, CH₃Br has a bigger and more polarisable electron cloud, stronger instantaneous dipole - induced dipole attraction between molecules, need more energy to overcome hence higher boiling point than CH₃Cl.

Question 4

Answer: D

Topic: Chemical Bonding

Explanation:

By considering the number of electrons around central atom via their dot-cross diagrams, we can determine nitrogen in NH₄⁺, carbon in CO₂ and carbon in HCHO all have 8 shared electrons.

Question 5

Answer: B

Topic: Chemical Bonding

Explanation:

C-F bond is polar and has dipole moment along its bond.

By considering the shape of molecules and their dipole moments due to C-F bonds, we can determine 1,1-difluoroethene and cis-1,2-difluoroethene are polar.

Question 6

Answer: D

Topic: Atomic Structure

Explanation:

We have to draw out the valence shell electronic configuration via electron in box diagram for Period 3 elements.

From the electronic configurations we can determine that:

P - number of elements with only 1 half filled orbital are Na, Al, Cl (3 elements)

Q - number of elements with only 1 fully filled orbital are Mg, Al, Si, P (4 elements)

Question 7

Answer: A

Topic: Group 2 Elements

Explanation:

Statement 1 is true as down the group, E value is more negative, metals are more likely oxidised hence more reducing.

Statement 2 is true as down the group, size of metal cation increases and charge density decreases. Metal cations become less polarising and distort electron cloud of carbonate to a smaller extent. The bonds within carbonate are relatively more stable and need more energy to break. Hence thermal stability increases.

Statement 3 is false as charge density of cation should decrease due to increasing size of cation.

Question 8

Answer: C

Topic: Atomic Structure

Explanation:

Percentage abundance of ²⁸Si is 92.23%

Let percentage abundance of ²⁹Si be x%, hence percentage abundance of ³⁰Si is (7.77 - x)%

We can then determine relative atomic mass in terms of x and solve for x.

Question 9

Answer: A

Topic: Energetics

Explanation:

NaOH is the limiting reagent so 0.1 mol of NaOH will form 0.1 mol of water.

Heat absorbed by solution = mass of water (150) x c (4.18) x change in temperature (9) = 5.643 kJ = heat released by neutralisation.

Hence enthalpy change of neutralisation can be solved.

Question 10

Answer: A

Topic: Chemical Bonding

Explanation:

Lattice energy is directly proportionate to charge of cation x charge of anion and inversely proportionate to radius of cation + radius of anion.

Ca⁺ has smaller charge and bigger size hence lattice energy of CaCl should be the smallest.

Mg²⁺ has bigger charge and smaller size hence lattice energy of MgCl₂ should be the largest.

Back to other 2023 A Level Paper 1 Questions

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