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Botswana JCE Science (Syllabus 14) study materials
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Botswana JCE Science (Syllabus 14) practice questions

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Question 1Scientific skills and processes

A learner measures the length of a metal rod as 12.5 cm using a ruler marked in millimetres. Which statement best describes this measurement?

  1. It has two significant figures and a precision of 0.01 cm
  2. It has three significant figures and a precision of 0.1 cm Correct answer.
  3. It has one significant figure and a precision of 0.5 cm
  4. It has four significant figures and a precision of 1 cm

Explanation

All three digits in 12.5 are meaningful, so the value has three significant figures. The smallest division on the ruler is one millimetre, which equals 0.1 cm, so that is the precision of the reading.

Question 2Scientific skills and processes

A student writes a hypothesis before an investigation. Which statement is the best example of a testable hypothesis?

  1. Plants need water to stay healthy
  2. Plants watered with 50 cm³ daily will grow taller than plants watered with 10 cm³ daily Correct answer.
  3. Water is the most beautiful substance on Earth
  4. Plants are interesting organisms to study

Explanation

A testable hypothesis predicts a measurable relationship between variables that can be checked by experiment. It names the treatment levels and the outcome to be measured, so results can support or reject it.

Question 3Scientific skills and processes

In an experiment, the variable that the investigator deliberately changes is called the:

  1. control variable
  2. constant variable
  3. independent variable Correct answer.
  4. dependent variable

Explanation

The independent variable is the factor the investigator chooses to alter between trials. Its effect is observed by measuring the dependent variable while other factors are held constant.

Question 4Scientific skills and processes

Which instrument would be most suitable for measuring the volume of a liquid to the nearest 0.1 cm³ accurately?

  1. A boiling tube
  2. A 50 cm³ measuring cylinder Correct answer.
  3. A 250 cm³ beaker
  4. A conical flask

Explanation

A measuring cylinder is graduated to allow readings to about 0.1 cm³ and is designed for volume measurement. Beakers, boiling tubes and conical flasks carry only rough graduations for approximate volumes.

Question 5Scientific skills and processes

A class records the time for a pendulum to make 20 swings. Why is timing 20 swings better than timing one swing?

  1. It removes the need to repeat the experiment
  2. It changes the independent variable
  3. It reduces the effect of reaction-time error on the result Correct answer.
  4. It makes the pendulum swing faster

Explanation

Human reaction time causes a similar absolute error at the start and stop of timing. Spreading that error over many swings and then dividing gives a much smaller error per swing.

Question 6Scientific skills and processes

Which of the following is a safe laboratory practice when heating a liquid in a test tube?

  1. Fill the tube completely to the top
  2. Point the mouth away from people and heat gently Correct answer.
  3. Point the mouth of the tube towards a partner
  4. Seal the tube with a stopper before heating

Explanation

Heating a liquid can cause it to spit or boil over, so the mouth must face away from everyone. Gentle heating and leaving space for expansion reduce the risk of sudden ejection.

Question 7Scientific skills and processes

A bar chart is most appropriate for displaying which type of data?

  1. Data recorded every second for ten minutes
  2. Continuous data such as temperature changing with time
  3. Categorical data such as the number of learners choosing each favourite metal Correct answer.
  4. Data with two continuous variables

Explanation

Bar charts suit categorical or discrete data where the categories are separate and unordered. Continuous data are better shown on a line graph that reveals trends.

Question 8Scientific skills and processes

A student measures the mass of a stone three times and obtains 24.2 g, 24.3 g and 24.2 g. What does this pattern show about the readings?

  1. They are accurate but not precise
  2. They are both precise and definitely accurate
  3. They are precise but may still be inaccurate Correct answer.
  4. They are neither precise nor accurate

Explanation

The readings agree closely with one another, which shows good precision. Precision alone does not prove accuracy, because all readings could share the same systematic error such as a zero error on the balance.

Question 9Scientific skills and processes

A learner wants to find out whether light intensity affects the rate of photosynthesis in pondweed. Which variable should be measured as the dependent variable?

  1. The distance of the lamp from the plant
  2. The mass of pondweed used
  3. The number of bubbles produced per minute Correct answer.
  4. The temperature of the water

Explanation

The dependent variable is the response being measured, which here is the rate of gas release. Counting bubbles per minute gives a numerical measure of that rate.

Question 10Scientific skills and processes

Why is a control group included in an investigation testing a fertiliser on plant growth?

  1. To increase the total number of plants measured
  2. To make the plants grow faster
  3. To provide a baseline for comparison without the fertiliser Correct answer.
  4. To replace the need for repeated measurements

Explanation

A control group is treated identically except that it does not receive the test treatment. Comparing the treated group with this baseline shows whether the fertiliser itself caused any difference.

Question 11Scientific skills and processes

A student plots a graph of extension against load for a spring and obtains a straight line through the origin. What conclusion is best supported?

  1. Extension is directly proportional to load within the range tested Correct answer.
  2. Load depends on the colour of the spring
  3. Extension decreases as load increases
  4. The spring cannot obey any law

Explanation

A straight line passing through the origin means the two quantities increase in the same ratio. That is the definition of direct proportionality within the tested range.

Question 12Scientific skills and processes

A learner measures the diameter of a wire with a micrometer screw gauge and records 0.48 mm. The instrument has a zero error of +0.03 mm. What is the corrected diameter?

  1. 0.45 mm Correct answer.
  2. 0.48 mm
  3. 0.51 mm
  4. 0.03 mm

Explanation

A positive zero error means the instrument reads too high, so the error must be subtracted from the recorded value. Subtracting 0.03 mm from 0.48 mm gives 0.45 mm.

Question 13Scientific skills and processes

Which action would most improve the reliability of an experiment measuring the melting point of a solid?

  1. Changing the heating rate between trials
  2. Repeating the measurement several times and averaging Correct answer.
  3. Recording the result only once carefully
  4. Using a larger sample of the solid

Explanation

Reliability concerns how consistent repeated results are. Repeating the procedure and averaging reduces the influence of random variation and gives a more dependable value.

Question 14Scientific skills and processes

During a field survey, a group counts the number of insects on leaves by choosing leaves without looking at them first. Why is this sampling method used?

  1. To make counting quicker than any other method
  2. To increase the number of insects present
  3. To ensure only large insects are counted
  4. To reduce bias so the sample represents the whole area Correct answer.

Explanation

Random selection prevents the investigator from favouring particular leaves, which could distort the result. A sample chosen without bias is more likely to represent the whole population.

Question 15Scientific skills and processes

A table of results shows temperature readings of 21, 23, 22, 24 and 23 degrees Celsius. What is the mean temperature?

  1. 22.6 degrees Celsius Correct answer.
  2. 23.0 degrees Celsius
  3. 21.0 degrees Celsius
  4. 24.0 degrees Celsius

Explanation

The mean is found by adding all the readings and dividing by the number of readings. The total is 113, and dividing by 5 gives 22.6 degrees Celsius.

Question 16Scientific skills and processes

A learner estimates the mass of a small stone as 30 g. The balance shows 24 g. What is the percentage error of the estimate?

  1. 20 percent
  2. 6 percent
  3. 25 percent Correct answer.
  4. 80 percent

Explanation

Percentage error compares the size of the error with the accepted value. The error is 6 g, and 6 divided by 24 multiplied by 100 gives 25 percent.

Question 17Scientific skills and processes

Which sequence correctly orders the steps of a scientific investigation?

  1. Collect data, state the problem, draw a conclusion, form a hypothesis
  2. Draw a conclusion, collect data, state the problem, form a hypothesis
  3. Form a hypothesis, draw a conclusion, state the problem, collect data
  4. State the problem, form a hypothesis, collect data, draw a conclusion Correct answer.

Explanation

An investigation begins by identifying a question or problem, then proposing a testable explanation. Data are then gathered and analysed before a conclusion is drawn.

Question 18Scientific skills and processes

Two groups measure the boiling point of a liquid. Group A obtains 98, 99 and 98 degrees Celsius. Group B obtains 100, 100 and 100 degrees Celsius. The accepted value is 100 degrees Celsius. Which statement is correct?

  1. Group A is more accurate but less precise than Group B Correct answer.
  2. Group B is less accurate but more precise than Group A
  3. Group A is more precise but less accurate than Group B
  4. Both groups are equally accurate and precise

Explanation

Group A's readings cluster tightly, so they are precise, but they sit below the accepted value, so they are inaccurate. Group B's readings hit the accepted value exactly, making them both accurate and precise.

Question 19Scientific skills and processes

A graph of distance against time for a moving trolley is a straight line with a positive slope. What does the slope of the line represent?

  1. The speed of the trolley Correct answer.
  2. The force on the trolley
  3. The acceleration of the trolley
  4. The mass of the trolley

Explanation

Slope equals the change in the vertical quantity divided by the change in the horizontal quantity. Here that is distance divided by time, which is speed.

Question 20Scientific skills and processes

A student measures the volume of an irregular stone by displacement. The water level rises from 40 cm³ to 55 cm³. Which additional precaution most improves the validity of the result?

  1. Using a larger stone
  2. Drying the stone before lowering it into the water
  3. Reading the scale from above
  4. Making sure the stone is fully submerged and no water splashes out Correct answer.

Explanation

The displacement method assumes that the rise in level equals the stone's volume. Full submersion and no loss of water ensure that only the stone causes the change.

Question 21Scientific skills and processes

A learner investigates how the angle of a ramp affects the distance a toy car travels. Which pair of variables is correctly identified?

  1. Independent: ramp angle; dependent: mass of the car
  2. Independent: distance travelled; dependent: ramp angle
  3. Independent: ramp angle; dependent: distance travelled Correct answer.
  4. Independent: mass of the car; dependent: ramp angle

Explanation

The investigator sets the ramp angle, so it is the independent variable. The distance the car travels is the response measured, making it the dependent variable.

Question 22Scientific skills and processes

A group repeats a measurement of the density of a metal and obtains 7.8, 7.9, 7.8 and 9.6 g/cm³. The accepted value is 7.9 g/cm³. What is the best interpretation of these results?

  1. The experiment is invalid because one value differs
  2. The accepted value must be wrong
  3. The value 9.6 is an outlier and should be checked before averaging Correct answer.
  4. All four values should be averaged without question

Explanation

Three readings agree closely with the accepted value while one is far away, suggesting a recording or procedural error. Anomalous results should be investigated and, if explained, excluded before calculating a mean.

Question 23Scientific skills and processes

A student claims that a fertiliser increases crop yield because plants given fertiliser grew taller than plants given none. Which additional evidence would most strengthen this causal claim?

  1. Repeating the trial with several plants per group and controlling water and light Correct answer.
  2. Recording the height only of the tallest plant
  3. Using a different type of plant in each group
  4. Measuring the plants on a sunnier day

Explanation

A causal claim is stronger when the result is repeatable and alternative explanations are ruled out. Replication increases confidence, and controlling water and light ensures the fertiliser is the only difference.

Question 24Scientific skills and processes

An investigation reports that increasing the concentration of acid increased the rate of reaction, based on one trial at each concentration. What is the main weakness of this conclusion?

  1. The rate of reaction cannot be measured
  2. The concentration was not measured
  3. There were no repeated trials, so the results may not be reliable Correct answer.
  4. The acid was the dependent variable

Explanation

A single trial at each concentration gives no indication of random variation, so the pattern could be a chance result. Repeating trials at each concentration would show whether the trend is consistent.

Question 25Scientific skills and processes

A graph shows temperature rising with time and then levelling off during melting. What is the best explanation for the flat section?

  1. The substance is losing heat to the surroundings only
  2. The temperature has reached the maximum scale value
  3. The thermometer stopped working
  4. Energy is being used to change state rather than raise temperature Correct answer.

Explanation

During a change of state, supplied energy breaks the forces between particles instead of increasing their average kinetic energy. Since temperature reflects average kinetic energy, it stays constant until melting is complete.

Question 26Scientific skills and processes

A learner writes a plan for an experiment but does not state what she expects to find. Which part of the scientific report is missing?

  1. The safety precautions
  2. The method steps
  3. The list of apparatus
  4. The prediction or hypothesis Correct answer.

Explanation

A scientific report normally contains a question, a prediction (hypothesis), a list of apparatus, a method, results and a conclusion. The prediction states what the learner expects the results to show and why. Without it the investigation has no stated idea to test, so this is the missing part.

Question 27Scientific skills and processes

A learner records the length of a leaf as 6.5 cm using a ruler marked in millimetres. Which statement about this reading is correct?

  1. It is accurate because it has a decimal place
  2. It is exact because a ruler was used
  3. It has no uncertainty because the leaf was measured once
  4. It is precise to the nearest 0.1 cm but may still be inaccurate Correct answer.

Explanation

A ruler marked in millimetres allows a reading estimated to about one tenth of a centimetre, so 6.5 cm shows the precision of the instrument. Precision describes how finely a value is read, while accuracy describes how close the value is to the true length. A precise reading can still be inaccurate if the ruler is faulty or the leaf was misaligned.

Question 28Scientific skills and processes

A learner wants to compare the growth of plants in four different soil types. Which type of graph is most suitable for showing the final heights for the four soils?

  1. A pie chart
  2. A bar chart Correct answer.
  3. A scatter graph
  4. A line graph

Explanation

Soil type is a category, not a continuous numerical quantity, so the heights are compared as separate bars. A bar chart displays discrete categories clearly and allows heights to be compared at a glance. Line graphs and scatter graphs are used where both variables are numerical and continuous.

Question 29Scientific skills and processes

Which instrument is most suitable for measuring the volume of a liquid to the nearest 0.1 cm³?

  1. A measuring cylinder Correct answer.
  2. A test tube
  3. A conical flask
  4. A beaker

Explanation

A measuring cylinder carries a graduated scale with fine divisions, so liquid volumes can be read to about 0.1 cm³. Beakers, flasks and test tubes have only rough markings for approximate volumes. Choosing the correct instrument improves the precision of the results.

Question 30Scientific skills and processes

A learner measures the time for a pendulum to make 20 swings instead of 1 swing, then divides by 20. Why does this improve the result?

  1. It makes the pendulum swing faster
  2. It removes friction from the pendulum
  3. It reduces the effect of reaction-time error on each swing Correct answer.
  4. It changes the independent variable

Explanation

Human reaction time causes a relatively large error when timing a single short swing. Timing many swings gives a longer total time, so the fixed reaction-time error becomes a smaller fraction of the measured value. Dividing by the number of swings then gives a more reliable value for one swing.

Question 31Scientific skills and processes

A learner heats a solid and records its temperature every 30 seconds. Which table heading is written correctly for the temperature column?

  1. Temperature °C
  2. Temperature / °C Correct answer.
  3. Temperature in degrees
  4. °C Temperature

Explanation

A results table heading should name the quantity and give its unit after a slash, for example Temperature / °C. This convention makes clear that the numbers in the column are in degrees Celsius. Headings without a clear unit convention can cause confusion when results are compared or plotted.

Question 32Scientific skills and processes

A learner wants to test whether the concentration of sugar solution affects the mass of potato chips placed in it. Which is the dependent variable?

  1. The concentration of the sugar solution
  2. The time the chips are left in the solution
  3. The change in mass of the potato chips Correct answer.
  4. The volume of solution used

Explanation

The dependent variable is the quantity that is measured as an outcome of changing the independent variable. Here the sugar concentration is deliberately changed, so the resulting change in mass of the potato chips is what is measured. Volume and time must be kept constant as control variables.

Question 33Scientific skills and processes

A group measures the mass of a metal block with a balance that reads 0.3 g when empty. Their recorded mass is 25.3 g. What is the corrected mass of the block?

  1. 24.7 g
  2. 25.0 g Correct answer.
  3. 25.3 g
  4. 25.6 g

Explanation

When an instrument has a zero error, the reading includes an extra amount even when nothing is placed on it. The empty balance reading of 0.3 g must be subtracted from the measured value. Subtracting gives 25.3 minus 0.3, which equals 25.0 g.

Question 34Scientific skills and processes

A learner measures the length of a rod five times and obtains 12.4, 12.5, 12.4, 12.6 and 12.4 cm. Which statement best describes these results?

  1. They are both accurate and imprecise
  2. They are precise but may not be accurate Correct answer.
  3. They show a clear systematic error
  4. They are accurate but not precise

Explanation

The readings cluster closely together, which shows high precision because repeated values agree. However, without a known accepted value for the rod, accuracy cannot be confirmed. Close agreement among repeats does not prove that the readings are close to the true length.

Question 35Scientific skills and processes

A learner investigates how the height of a ramp affects the speed of a trolley. Which action would make the investigation a fair test?

  1. Using the same trolley and the same length of ramp each time Correct answer.
  2. Measuring the speed only once at each height
  3. Repeating only the highest ramp height
  4. Changing the ramp height and the trolley at the same time

Explanation

In a fair test only the independent variable, the ramp height, should change while other factors are kept constant. Using the same trolley and the same ramp keeps mass and travel distance controlled so the effect of height can be isolated. Repeating each measurement also improves reliability.

Question 36Scientific skills and processes

A graph of temperature against time for a cooling liquid is a curve that becomes flatter as time goes on. What does the decreasing slope indicate?

  1. The thermometer has a zero error
  2. The liquid is gaining heat from the surroundings
  3. The temperature is rising more quickly
  4. The rate of cooling becomes slower as time passes Correct answer.

Explanation

The slope of a temperature-time graph represents the rate of change of temperature. A slope that becomes less steep means the temperature is changing more slowly with each passing interval. This is expected because the temperature difference between the liquid and the surroundings falls as the liquid cools.

Question 37Scientific skills and processes

A learner tests whether a detergent affects the rate of enzyme activity. She uses one test tube and adds detergent halfway through the experiment. Why is this design weak?

  1. Detergents always stop enzyme activity
  2. Enzymes cannot work in test tubes
  3. The effect of the detergent is mixed with the effect of time Correct answer.
  4. The test tube should have been larger

Explanation

A valid experiment compares conditions that differ only in the independent variable. Adding detergent midway means the early and late readings differ in both time and detergent, so the cause of any change cannot be identified. Separate control and test tubes run side by side would avoid this confusion.

Question 38Scientific skills and processes

A learner collects data on the number of leaves on plants grown at five different light intensities. Which step is most important before drawing a conclusion?

  1. Checking whether the data show a consistent trend and repeating the measurements Correct answer.
  2. Discarding results that do not fit the prediction
  3. Choosing the plant with the most leaves as the result
  4. Rounding all leaf counts to the nearest ten

Explanation

Conclusions must be based on patterns that are supported by the evidence and can be reproduced. Checking for a consistent trend and repeating measurements tests whether the pattern is reliable rather than accidental. Results that contradict a prediction should be examined, not removed.

Question 39Scientific skills and processes

Two learners measure the same volume. Learner A uses a 100 cm³ measuring cylinder and records 62 cm³. Learner B uses a 10 cm³ measuring cylinder and records 62.0 cm³. Which explanation is best?

  1. Learner A's reading is more accurate because the cylinder is larger
  2. Both readings have identical uncertainty
  3. Learner B's instrument has finer divisions, giving greater precision Correct answer.
  4. Learner B's reading must be wrong because the volume exceeds the cylinder size

Explanation

A smaller measuring cylinder has finer graduations, so it can be read to a smaller fraction of a cubic centimetre. This gives a more precise reading, shown by the extra decimal place. Precision depends on the instrument scale, not on the physical size of the vessel alone.

Question 40Scientific skills and processes

An investigation reports that a fertilizer increased plant height by 2 cm, but the heights of untreated plants varied by 5 cm between repeats. What is the best interpretation?

  1. The fertilizer definitely increased growth by 2 cm
  2. The untreated plants were unhealthy
  3. The experiment should be repeated with only one plant
  4. The difference is smaller than the natural variation, so the effect is not convincing Correct answer.

Explanation

A measured difference can only be trusted if it is larger than the random variation within each group. Here the natural spread of 5 cm is greater than the 2 cm difference, so the effect could easily be due to chance. More repeats and a larger sample would help decide whether the fertilizer really has an effect.

Question 41Matter and materials

Which property is characteristic of a solid but not of a liquid?

  1. It has a fixed shape. Correct answer.
  2. It can be compressed easily.
  3. Its particles are in constant motion.
  4. It has a fixed volume.

Explanation

Particles in a solid are held in fixed positions by strong forces, so a solid keeps its own shape. A liquid has a fixed volume but takes the shape of its container because its particles can slide past one another. Both states have moving particles and are only slightly compressible.

Question 42Matter and materials

A gas is described as having no fixed shape and no fixed volume. Which statement best explains this?

  1. Its particles attract each other strongly at all times.
  2. Its particles are far apart and move quickly in all directions. Correct answer.
  3. Its particles are packed closely in a regular pattern.
  4. Its particles are held by strong forces in fixed positions.

Explanation

In a gas the particles are widely separated with weak forces between them, so they move rapidly and randomly. They spread out to fill any container, giving the gas neither fixed shape nor fixed volume. Close packing and fixed positions describe solids instead.

Question 43Matter and materials

What happens to the particles of a liquid when it is heated?

  1. They become smaller and lose mass.
  2. They move faster and the spaces between them increase. Correct answer.
  3. They change into a different element.
  4. They stop moving and lock into fixed positions.

Explanation

Heating transfers energy to the particles, so their average speed and kinetic energy increase. They push slightly further apart, which is why the liquid expands and may eventually boil. The particles themselves do not shrink or change into a new element.

Question 44Matter and materials

Which of these changes of state releases energy to the surroundings?

  1. Freezing Correct answer.
  2. Boiling
  3. Evaporation
  4. Melting

Explanation

Freezing is the change from liquid to solid, in which particles lose kinetic energy and form stronger bonds. The energy removed is released to the surroundings, so freezing warms its surroundings. Melting, boiling and evaporation all absorb energy instead.

Question 45Matter and materials

A mixture of sand and water is best separated by which method?

  1. Chromatography
  2. Evaporation to dryness
  3. Distillation
  4. Filtration Correct answer.

Explanation

Sand is insoluble in water, so it can be trapped by filter paper while the water passes through as the filtrate. Filtration separates an insoluble solid from a liquid. Distillation and evaporation would remove the water rather than simply recover the sand.

Question 46Matter and materials

Which statement describes a chemical change?

  1. A new substance being formed with different properties Correct answer.
  2. Ice melting in a warm room
  3. Salt dissolving in water
  4. Sugar being ground into powder

Explanation

A chemical change produces one or more new substances with properties different from the starting materials. Melting, dissolving and grinding only change the physical form of the same substance. Such changes are usually reversible and do not create new materials.

Question 47Matter and materials

Which of the following is a compound rather than a mixture?

  1. Brass
  2. Air
  3. Sea water
  4. Carbon dioxide Correct answer.

Explanation

A compound contains two or more elements chemically combined in fixed proportions, as in carbon dioxide, which is made of carbon and oxygen joined together. Its components cannot be separated by simple physical means. Air, sea water and brass are mixtures.

Question 48Matter and materials

The particles of a gas are best described as moving in which way?

  1. Sliding over one another in a fixed volume
  2. Vibrating about fixed positions
  3. Staying still and touching each other
  4. Moving quickly and randomly with large spaces between them Correct answer.

Explanation

Gas particles have the most kinetic energy of the three states and travel rapidly in straight lines until they collide. The spaces between them are large compared with the particles themselves. Fixed positions and sliding describe solids and liquids respectively.

Question 49Matter and materials

A student heats a solid until it melts and records the temperature every minute. During melting the temperature stays constant even though heating continues. What is the energy being used for?

  1. Making the particles move closer together
  2. Increasing the average kinetic energy of the particles
  3. Breaking the forces that hold the particles in their fixed positions Correct answer.
  4. Creating new chemical elements

Explanation

At the melting point the added energy is used as latent heat to overcome the forces holding particles in the solid lattice. Because the energy does not increase average particle speed, the temperature does not rise until all the solid has melted. Only after melting does the temperature climb again.

Question 50Matter and materials

Why does a wet cloth dry faster on a windy day than on a still day?

  1. The wind lowers the boiling point of the water.
  2. The wind raises the temperature of the water above 100 °C.
  3. The wind increases the surface area of the cloth.
  4. The wind removes water vapour, allowing more evaporation. Correct answer.

Explanation

Evaporation depends partly on how much vapour is already in the air near the surface. Wind blows away the moist air, keeping the vapour concentration low so that more water molecules can escape. It does not change the boiling point or the surface area of the cloth.