Home / iGCSE / Coordinated Sciences / C10.2 Air quality and climate Paper 4

CIE iGCSE Co-Ordinated Science C10.2 Air quality and climate Exam Style Questions Paper 4

CIE iGCSE Co-Ordinated Science Paper 4 - All Chapters

Question

Hydrogen-oxygen fuel cells use hydrogen and oxygen to produce electricity.
(a) The reactions at the electrodes in a hydrogen-oxygen fuel cell are shown.
anode: \(H_2 \rightarrow 2H^+ + 2e^-\)
cathode: \(4H^+ + O_2 + 4e^- \rightarrow 2H_2O\)
(i) State the name of the only chemical product in a hydrogen-oxygen fuel cell. ______
(ii) Explain why the reaction between hydrogen and oxygen in a fuel cell involves oxidation. ______
(b) Table 6.1 shows information about using a hydrogen-oxygen fuel cell and a petrol engine for powering cars.
Suggest which fuel would be most suitable to power a car. Explain your answer.
(c) Oxides of nitrogen are formed in petrol car engines.
(i) State one adverse effect of oxides of nitrogen.
(ii) Explain how oxides of nitrogen form in petrol car engines.
(iii) Oxides of nitrogen and carbon monoxide are removed from a car engine by a catalytic converter.
Complete the balanced symbol equation for the reaction that takes place.
2CO + 2NO → ______ + ______

Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):

• Topic C4.2 — Hydrogen-oxygen fuel cells
• Topic C10.2 — Air quality and climate

▶️ Answer/Explanation

(a)(i) water
The only product formed in a hydrogen-oxygen fuel cell is water, making it an environmentally friendly energy source.

(a)(ii) loss of electrons (from hydrogen)
Oxidation is defined as the loss of electrons. At the anode, hydrogen atoms lose electrons to form protons, so they are oxidised.

(b)

Any three from:

Hydrogen-oxygen fuel cell:

  • cheaper (than petrol) to refill
  • short refuelling time
  • good range
  • no pollution

OR

Petrol engine:

  • high availability / excellent availability
  • quicker refuelling
  • longer range (than hydrogen-oxygen)

The most suitable fuel depends on the criteria prioritised. Hydrogen-oxygen fuel cells produce no pollution but have limited availability, while petrol engines have excellent availability and slightly longer range but produce harmful emissions.

(c)(i) acid rain / respiratory problems
Oxides of nitrogen dissolve in rainwater to form acid rain, which damages buildings, soil, and aquatic ecosystems. They also irritate the respiratory system.

(c)(ii) nitrogen reacts with oxygen ; at high temperature (inside a car engine)
The high temperatures and pressures in car engines cause atmospheric nitrogen and oxygen to react, forming nitrogen oxides.

(c)(iii) 2CO + 2NO → 2CO₂ + N₂
In catalytic converters, carbon monoxide reduces nitrogen oxides, producing harmless carbon dioxide and nitrogen gas. This prevents toxic gases from being released into the atmosphere.

Question

A sodium atom is represented with numbers next to its chemical symbol, as shown in Fig. 6.1.
(a) Complete Table 6.1 to show the structure of a sodium atom.
(b) Fig. 6.2 shows an outline of the Periodic Table. The letter E shows the position of an element in the Periodic Table. The letter E is not the chemical symbol of the element.
Predict the electronic configuration of element E. Tick \((\checkmark)\) one box.
☐ 2.8
☐ 2.8.2
☐ 2.8.8
☐ 2.8.8.1
(c) Carbon-12 and carbon-13 are two isotopes of the element carbon. These isotopes of carbon have the same chemical properties. Explain why.
(d) State the type of oxide formed when carbon, a non-metal, reacts with oxygen to produce carbon dioxide, \(\text{CO}_2\).
(e) Carbon dioxide is a greenhouse gas and causes global warming. Complete the sentences to describe how carbon dioxide causes global warming. Use words from the list.
Each word can be used once, more than once, or not at all.
absorbed       reflected       refracted       stored
Energy from the Sun reaches the Earth’s surface. Some energy is ______________ back into space. Most of the energy is ______________ by the Earth’s surface, causing an increase in temperature. The warm Earth emits energy. Some of this emitted energy is then ______________ by greenhouse gases. When this energy is re-emitted, it can be transferred back to the Earth’s surface.
(f) Some coal burns to make \(11000\text{ g}\) of carbon dioxide gas. Calculate the volume occupied by \(11000\text{ g}\) of carbon dioxide gas. The volume of one mole of any gas is \(24\text{ dm}^3\) at room temperature and pressure (r.t.p.).
[\(A_r: \text{C}, 12; \text{O}, 16\)]

Topic codes:

• Topic C2.2 — Atomic structure and the Periodic Table (Part (a) & (b))
• Topic C2.3 — Isotopes (Part (c))
• Topic C7.2 — Oxides (Part (d))
• Topic C10.2 — Air quality and climate / Global warming (Part (e))
• Topic C3.3 — The mole and the Avogadro constant (Part (f))

▶️ Answer/Explanation

(a) Complete Table 6.1:

Sodium has 11 protons (atomic number = 11), 11 electrons (neutral atom), and 23 − 11 = 12 neutrons.

(b) ☑ 2.8.2

Element E is in Period 3 (three electron shells) and Group II (two outer-shell electrons). Therefore, the electronic configuration is 2,8,2.

(c) Isotopes of carbon have the same chemical properties because they have the same number of electrons / the same electronic configuration. Chemical properties depend on the number and arrangement of electrons in the atom.

(d) Acidic oxide — carbon dioxide is an acidic oxide because it reacts with bases to form salts and water.

(e) Energy from the Sun reaches the Earth’s surface. Some energy is reflected back into space. Most of the energy is absorbed by the Earth’s surface, causing an increase in temperature. The warm Earth emits energy. Some of this emitted energy is then absorbed by greenhouse gases. When this energy is re-emitted, it can be transferred back to the Earth’s surface.

(f) \(M_r\) of CO₂ = 12 + (2 × 16) = 44

Moles of CO₂ = 11000 ÷ 44 = 250 mol

Volume of CO₂ = 250 × 24 = 6000 dm³

More CIE iGCSE Co-Ordinated Science Paper 4 Questions..
Scroll to Top