2024 Cambridge IGCSE Science - Combined (0653) Practice Paper with Answers

An object of mass \(m\) travels at a constant speed \(v\) and has kinetic energy \(E\). What is the kinetic energy of an object of mass \(\frac{1}{2}m\) traveling at a speed of \(2v\)?

Which row correctly describes the colour changes when aqueous chlorine is added to separate aqueous solutions of potassium bromide and potassium iodide?

A ray of light in air is incident on the surface of a glass block. Which row correctly describes the change in speed of the light ray and the direction of its bending as it enters the glass block?

Which row correctly matches the site of fertilisation and the site of embryo implantation in the female reproductive system?

Two resistors of resistance \(R_1\) and \(R_2\) are connected in parallel to a cell. The resistance of \(R_1\) is greater than the resistance of \(R_2\). Which statement about the current in the resistors and the potential difference (p.d.) across them is correct?

An unknown salt solution is tested as follows:
- Addition of dilute nitric acid followed by aqueous silver nitrate produces a white precipitate.
- Addition of aqueous sodium hydroxide produces a light blue precipitate that is insoluble in excess.
What is the identity of the salt?

Which combination of environmental conditions will result in the highest rate of transpiration in a healthy plant?

One molecule of a gaseous alkane with formula \(C_{12}H_{26}\) undergoes cracking to produce one molecule of ethene, \(C_2H_4\), and one molecule of another hydrocarbon. What is the formula of this other hydrocarbon?

Which row correctly matches an adaptive feature of a human sperm cell to its function?

A rectangular block of concrete has a weight of \(240\text{ N}\) and dimensions \(0.50\text{ m} \times 0.40\text{ m} \times 0.20\text{ m}\). What is the maximum pressure the block can exert when resting on a flat horizontal surface?

A student performs paper chromatography on a food dye. The solvent front travels \(8.0\text{ cm}\) from the baseline. One of the coloured spots has an \(R_f\) value of \(0.35\). What is the distance travelled by this spot from the baseline?

A sound wave of frequency \(1200\text{ Hz}\) travels through a liquid at a speed of \(1500\text{ m/s}\). What is the wavelength of this sound wave in the liquid?

A battery delivers a constant current of \(0.40\text{ A}\) to a circuit for \(5.0\text{ minutes}\). How much charge passes through the circuit during this time?

Which statement correctly describes a difference between transition elements, such as copper, and alkali metals, such as sodium?

A student wants to prepare a pure, dry sample of the insoluble salt lead(II) sulfate. Which pair of aqueous solutions should be mixed together to produce this salt by precipitation?

A hydrocarbon has the formula \(\text{C}_4\text{H}_8\). Which statement about this hydrocarbon is correct?

A crate of weight \(400\text{ N}\) is lifted vertically upwards at a constant speed of \(0.50\text{ m/s}\) by an electric motor. What is the useful power output of the motor?

In a paper chromatography experiment, a dye is analysed. The baseline is at \(0\text{ cm}\) and the solvent front reaches the \(12.0\text{ cm}\) mark. A component of the dye has an \(R_f\) value of \(0.75\). What is the distance of this spot from the baseline?

A sound wave travels through air with a speed of \(340\text{ m/s}\). The frequency of the sound is \(850\text{ Hz}\). What is the wavelength of this sound wave?

Which row correctly describes the features of a wind-pollinated flower?

A \(6.0\text{ V}\) power supply is connected across two resistors in parallel. The resistances of the resistors are \(12\ \Omega\) and \(6.0\ \Omega\). What is the total current in the circuit?

As we move down Group VII (the halogens) of the Periodic Table, how do the colour intensity and the reactivity of the elements change?

A student tests a solution of compound Y. Addition of aqueous sodium hydroxide produces a blue precipitate. Addition of dilute nitric acid followed by aqueous barium nitrate produces a white precipitate. What is the identity of compound Y?

What is the correct pathway taken by water as it moves through a plant from the soil?

Which row correctly contrasts the features of insect-pollinated and wind-pollinated flowers?

Which row correctly identifies the mineral ion required by plants to make chlorophyll and the direct symptom of its deficiency?

As we go down Group VII (the halogens) of the Periodic Table, how do the colour intensity, state at room temperature, and reactivity of the elements change?

An ideal battery of electromotive force (e.m.f.) 12 V is connected across a parallel combination of two resistors of resistance 4.0 \(\Omega\) and 12.0 \(\Omega\). What is the total current supplied by the battery?

An electric motor lifts a load of mass 50 kg vertically through a height of 12 m in a time of 15 s. The gravitational field strength g is 10 N/kg. What is the average useful power output of the motor?

A student reacts a known mass of zinc granules with an excess of dilute hydrochloric acid. Which change to the reaction conditions increases the initial rate of reaction without changing the total volume of hydrogen gas produced?

An unknown aqueous solution of salt X undergoes two tests: 1. When dilute nitric acid and aqueous silver nitrate are added, a white precipitate forms. 2. When aqueous sodium hydroxide is added, a green precipitate forms that is insoluble in excess. What is the chemical name of salt X?

A sound wave travels from air into a water pool. Which row describes how the speed, frequency, and wavelength of the sound wave change?

Which substances are present in a higher concentration in the blood of the umbilical artery than in the blood of the umbilical vein?

A student performs paper chromatography to identify the dyes present in a green food colouring. The solvent front travels 8.0 cm from the baseline. One of the separated spots travels a distance of 6.4 cm. What is the \(R_f\) value of this dye, and what does this indicate about its solubility in the mobile phase compared to a dye with an \(R_f\) value of 0.40?

A block of mass 12 kg is lifted vertically through a height of 5.0 m in a time of 4.0 s. The gravitational field strength, \(g\), is 10 N/kg. What is the useful power developed in lifting the block?

In a food chain, only a fraction of the energy entering one trophic level is transferred to the next. Which processes explain why herbivores only transfer about 10% of the energy they consume to carnivores?

1. Energy lost as heat from respiration.
2. Energy stored in organic molecules of uneaten parts of the plants.
3. Energy lost in egested waste (faeces).
4. Energy captured from sunlight by plants.

Which row correctly describes the trends in reactivity and physical properties of the Group VII elements (halogens) as the group is descended from chlorine to iodine?

A student is given an unknown solid, W. When dilute hydrochloric acid is added to W, a gas is evolved that turns limewater cloudy. When W is dissolved in water and treated with aqueous sodium hydroxide, a green precipitate is formed. What is the chemical formula of W?

An electromagnetic wave has a frequency of \(6.0 \times 10^{14}\text{ Hz}\) and travels at a speed of \(3.0 \times 10^8\text{ m/s}\) in a vacuum. What is the wavelength of this wave, and to which part of the electromagnetic spectrum does it belong?

A circuit contains a 6.0 V battery connected to two resistors in parallel. One resistor has a resistance of \(3.0\ \Omega\) and the other has a resistance of \(6.0\ \Omega\). What is the total current drawn from the battery?

Answer all parts of this question.

(a) (i) Define the term *fertilisation* as it applies to human reproduction. [1]

(ii) State the exact part of the female reproductive system where fertilisation typically occurs. [1]

(iii) Describe what happens to the number of chromosomes during this process. [1]

(b) Wind-pollinated grass flowers have structural adaptations to ensure successful pollination. These include long, feathery stigmas and pendulous anthers that hang outside the petals.

Explain how the structure of these stigmas and anthers are adapted for wind pollination. [3]

(c) Some plants can reproduce both sexually and asexually.

State three differences between the offspring produced by asexual reproduction and those produced by sexual reproduction in plants. [3]

Answer all parts of this question.

(a) An electric crane is used on a construction site to lift a concrete block of mass 150 kg vertically upwards. The block is lifted through a height of 8.0 m in a time of 12 s at a constant speed.

The gravitational field strength, \(g\), is 10 N/kg.

(i) Calculate the increase in gravitational potential energy (\(\Delta\text{GPE}\)) of the concrete block. Show your working. [2]

(ii) Calculate the useful power developed by the crane. State the unit of your answer. [3]

(b) The motor of the crane is actually supplied with 1500 W of electrical power.

(i) Explain why the electrical power supplied to the motor is greater than the useful power output calculated in (a)(ii). [2]

(ii) Calculate the efficiency of the crane. [2]

Answer all parts of this question.

(a) Potassium and sodium are Group I alkali metals.

(i) Describe the trend in reactivity of the alkali metals as the group is descended. [1]

(ii) Explain this trend in terms of atomic structure. [3]

(b) Chlorine is a Group VII halogen.

(i) Write a balanced chemical equation, including state symbols, for the reaction between aqueous potassium bromide and chlorine gas. [3]

(ii) Explain why a reaction does not occur when aqueous potassium chloride is mixed with iodine solution. [2]

Answer all parts of this question.

(a) A circuit contains a 12 V d.c. power supply connected to two resistors in parallel. Resistor \(R_1\) has a resistance of \(4.0\ \Omega\) and resistor \(R_2\) has a resistance of \(6.0\ \Omega\).

(i) Calculate the combined resistance of the two resistors connected in parallel. Show your working. [2]

(ii) Calculate the total current leaving the power supply. [2]

(iii) Calculate the current flowing through resistor \(R_1\). [2]

(b) A third resistor, \(R_3\), is now connected in series with the parallel combination.

State and explain the effect of this modification on:

(i) the total resistance of the circuit [2]

(ii) the total current in the circuit [1]

Answer all parts of this question.

(a) Describe the pathway and mechanism of water transport in a flowering plant from the soil, through the roots and stem, and out into the atmosphere. [4]

(b) A student sets up a potometer to measure the rate of transpiration of a leafy shoot under different conditions.

State and explain how the rate of transpiration changes when:

(i) the humidity of the surrounding air increases [2]

(ii) the temperature of the surrounding air increases [3]

Answer all parts of this question.

(a) Magnesium sulfate is a soluble salt. It can be prepared by reacting dilute sulfuric acid with insoluble magnesium carbonate.

(i) Write a balanced chemical equation for this reaction. State symbols are not required. [2]

(ii) Describe the steps involved in preparing a pure, dry sample of magnesium sulfate crystals starting from dilute sulfuric acid and solid magnesium carbonate. [5]

(b) State the test and observation used to confirm the presence of sulfate ions in the resulting solution. [2]

Answer all parts of this question.

(a) Electromagnetic waves travel through a vacuum at a constant speed of \(3.0 \times 10^8\text{ m/s}\).

(i) State one feature that is common to all electromagnetic waves, other than their speed in a vacuum. [1]

(ii) Microwaves are used for satellite communications.

Calculate the wavelength of a microwave signal with a frequency of \(1.5 \times 10^9\text{ Hz}\). Show your working. [2]

(b) Light travels from air into a rectangular glass block.

(i) Describe what happens to the speed, frequency, and wavelength of the light as it enters the glass block from air. [3]

(ii) Explain the process of refraction (bending of light) in terms of the wave speed at the boundary. [3]

Answer all parts of this question.

(a) Hexane (\(\text{C}_6\text{H}_{14}\)) is a saturated hydrocarbon.

(i) Define the term *hydrocarbon*. [1]

(ii) Draw the displayed structure of a hexane molecule showing all atoms and covalent bonds. [2]

(b) Cracking is used to break down larger, less useful alkane molecules into smaller, more useful alkenes and alkanes.

(i) Write a balanced chemical equation for the cracking of decane (\(\text{C}_{10}\text{H}_{22}\)) to produce one molecule of ethene (\(\text{C}_2\text{H}_4\)) and one other alkane molecule. [2]

(ii) Describe a chemical test to distinguish between the products of this cracking reaction (ethene and the other alkane product). State the test and the observations for both substances. [3]

(c) State one major environmental concern associated with the incomplete combustion of hydrocarbons in car engines. [1]

A toy cart of mass \(2.5\text{ kg}\) moves along a straight, horizontal track.
The cart starts from rest and accelerates uniformly to a speed of \(8.0\text{ m/s}\) in a time of \(5.0\text{ s}\).
It then travels at this constant speed of \(8.0\text{ m/s}\) for a further \(10\text{ s}\).

(a) (i) Calculate the acceleration of the cart during the first \(5.0\text{ s}\).
Show your working and state the unit.
[3]

(ii) Calculate the total distance travelled by the cart during the \(15\text{ s}\ interruption of its motion. Show your working. [3] (b) Calculate the kinetic energy of the cart when it is travelling at its constant speed of \)8.0\text{ m/s}\).
Show your working.
[2]

(c) State the relationship between work done, force and distance.
[1]

A student investigates the effect of light intensity on the rate of photosynthesis in the aquatic plant Cabomba. The apparatus is set up with a lamp placed at various distances from a boiling tube containing the plant in water. (a) (i) Fig. 1.1 shows a diagram of the ruler used to measure the distance of the lamp. The pointer on the lamp indicates its position on the ruler. State the distance, d, of the lamp shown in Fig. 1.1. d = .................... cm [1] (ii) The student counts the oxygen bubbles produced by the plant in one minute. Fig. 1.2 shows the bubbles observed in the test-tube during this period. Count and record the number of bubbles shown in Fig. 1.2. number of bubbles = .................... [1] (b) The student repeats the experiment for other distances. Table 1.1 shows the results. Table 1.1: Distance d / cm: [10, 15, 20, 25, 30], Bubble count in Minute 1: [42, 28, 19, (value from (a)(ii)), 8], Bubble count in Minute 2: [44, 30, 21, 13, 9], Average bubble count: [43.0, 29.0, 20.0, ...................., 8.5]. (i) Complete Table 1.1 by writing the bubble count from (a)(ii) and calculating the average bubble count at d = 25 cm. [2] (c) Plot a graph of the average bubble count (vertical axis) against the distance of the lamp d (horizontal axis) on the grid. Draw the curve of best fit. [3] (d) State the relationship between the distance of the lamp and the rate of bubble production. [1] (e) Identify one variable, other than the light intensity, that must be kept constant in this investigation, and explain how the student could keep it constant. [2]

A student investigates the thermal decomposition of a green powder, copper(II) carbonate. The student heats a sample of copper(II) carbonate in a crucible with a lid. (a) Fig. 2.1 shows the digital balance display for the mass of the crucible, lid, and residue after heating. State the mass shown on the balance in Fig. 2.1. mass = .................... g [1] (b) The student's recorded masses are: Mass of empty crucible and lid = 18.45 g, Mass of crucible, lid, and copper(II) carbonate before heating = 21.93 g. Calculate: (i) the mass of copper(II) carbonate heated. mass of copper(II) carbonate = .................... g [1] (ii) the mass of the copper(II) oxide residue obtained. mass of residue = .................... g [1] (iii) the mass of carbon dioxide gas lost during heating. mass of carbon dioxide lost = .................... g [1] (c) (i) The theoretical mass of carbon dioxide that should be lost from this sample is 1.24 g. Calculate the percentage yield of carbon dioxide gas. Show your working. percentage yield = .................... % [2] (ii) Suggest one reason why the calculated percentage yield might be less than 100%. [1] (d) Describe a chemical test, including the observation, to confirm that the gas evolved is carbon dioxide. test .................... observation .................... [2] (e) State one safety precaution the student should take when handling the hot crucible. [1]

A student investigates the cooling and solidifying of stearic acid. A boiling tube containing liquid stearic acid is placed in a beaker of cold water, and the temperature is recorded every minute. (a) Fig. 3.1 shows the thermometer reading at time t = 0.0 min. State the temperature shown on the thermometer in Fig. 3.1. temperature = .................... °C [1] (b) Table 3.1 shows the temperature, T, at various times, t. Table 3.1: Time t / min: [0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0], Temperature T / °C: [...................., 79.5, 75.0, 71.0, 69.5, 69.5, 69.5, 68.0, 65.5, 63.0, 61.0]. (i) Complete Table 3.1 by inserting the temperature at t = 0.0 min from (a). [1] (ii) On the grid, plot a graph of Temperature T (vertical axis) against Time t (horizontal axis). Draw a smooth curve of best fit. [4] (iii) State the melting point of stearic acid obtained from your graph and explain how the graph shows this value. melting point = .................... °C, explanation: .................... [2] (iv) State the state of matter of the stearic acid at t = 5.0 min. [1] (v) State one precaution that the student should take to avoid a parallax error when reading the thermometer. [1]

A student investigates the refraction of a ray of light as it passes from air into a semi-circular transparent plastic block. (a) Fig. 4.1 shows the path of a ray of light incident on the flat face of the block at point P. (i) On Fig. 4.1, draw the normal to the flat surface at point P. [1] (ii) Measure and record the angle of incidence, i, between the incident ray and the normal. i = .................... degrees [1] (iii) Measure and record the angle of refraction, r, between the refracted ray and the normal. r = .................... degrees [1] (b) The student repeats the experiment for other angles of incidence. Table 4.1 shows the results. Table 4.1: Angle of incidence, i / degrees: [20, 30, 40, 50, 60], Angle of refraction, r / degrees: [13, 19, ...................., 31, 35]. (i) Complete Table 4.1 by inserting your measured value of r from (a)(iii). [1] (ii) State the relationship between the angle of incidence and the angle of refraction. [1] (c) The refractive index, n, of the plastic block is given by the formula: n = sin(i) / sin(r). (i) Calculate the value of n for i = 30 degrees and r = 19 degrees. Show your working and give your answer to two significant figures. n = .................... [2] (ii) State why the refractive index, n, has no unit. [1] (d) State two sources of experimental error when tracing rays with pins or using a light box, and describe how to minimise them. [2]