MatterIB MYP Sciences: Topic test

20 questions, 54 marks

IB MYP Sciences

Matter topic test

Total 54 marks

Name

Class

Date

1
A lake in Norway freezes over in winter. In spring the ice melts, and on warm summer days water slowly evaporates from the surface of the lake even though the water is far below its boiling point.
(a)
Which statement describes the particles in liquid water in the lake?
[1 mark]
AThey are close together in a regular pattern and only vibrate.
BThey are close together in an irregular arrangement and can move past each other.
CThey are far apart and move quickly in all directions.
DThey are far apart and held in a fixed pattern.
(b)
Water at 15 °C slowly turns into water vapour at the surface of the lake. What is this change of state called?
[1 mark]
ABoiling
BCondensation
CEvaporation
DSublimation
(c)
Explain, in terms of particles and the forces between them, why ice melts when it absorbs energy from the warm air.
[2 marks]
Total for question 1: 4 marks
2
A football is pumped up in Rio de Janeiro on a cool morning and then left on a sunny beach all afternoon. The ball is sealed, so no air can escape, and its volume stays the same. By the afternoon the air inside the ball has warmed to 27 °C.
(a)
Why does the pressure of the air inside the ball increase as the air warms up?
[1 mark]
AThe air particles expand and become larger.
BThe air particles move more slowly and press harder on the wall.
CMore air particles enter the ball from outside.
DThe air particles move faster and hit the wall more often and with more force.
(b)
What is the temperature of the air in the ball on the Kelvin scale?
[1 mark]
A300 K
B246 K
C27 K
D373 K
(c)
A second football of the same size is pumped up with more air than the first. Explain, using the particle model, why the pressure inside the second ball is higher when both balls are at the same temperature.
[2 marks]
Total for question 2: 4 marks
3
In a demonstration in a school in Lima, a long horizontal glass tube is closed at both ends. A piece of cotton wool soaked in concentrated ammonia solution is pushed into one end of the tube and a piece soaked in concentrated hydrochloric acid is pushed into the other end at the same moment. Both give off a gas. After a few minutes a white ring of ammonium chloride forms inside the tube where the two gases meet. The tube is at 20 °C.
(a)
Explain, using the particle model, how ammonia gas spreads along the tube.
[3 marks]
(b)
The demonstration is repeated in a warm room at 35 °C. Predict how the time taken for the ring to form changes. Explain your prediction, and explain why the ring still takes several minutes to form although gas particles move at hundreds of metres per second.
[4 marks]
Total for question 3: 7 marks
4
A gas company in Rotterdam separates the gases in air. Air is first cooled to about −200 °C, when it becomes a liquid mixture. The liquid is then warmed slowly in a tall column. Nitrogen (boiling point −196 °C) boils off first, then argon (boiling point −186 °C), and oxygen (boiling point −183 °C) boils last. Each gas is collected separately. The process uses large amounts of electricity for cooling. Oxygen is supplied to hospitals and steelworks, nitrogen to fertiliser factories and food packers, and argon to welders.
(a)
Explain how fractional distillation separates the gases in liquid air. In your answer refer to the particles and to the forces between them.
[6 marks]
(b)
Discuss and evaluate the social, economic and environmental implications of separating the gases in air on a large scale. Finish with a justified conclusion.
[6 marks]
Total for question 4: 12 marks
5
A student in Wellington stirs a spoonful of blue copper(II) sulfate crystals into a beaker of water. The crystals disappear and a clear blue liquid forms. She then pours the liquid into a shallow dish and leaves it in a warm room for several days, and blue crystals form again in the dish.
(a)
What is the correct word for the copper(II) sulfate in the clear blue liquid?
[1 mark]
ASolvent
BSolution
CSolute
DResidue
(b)
Which statement about the clear blue liquid is correct?
[1 mark]
AIt is a mixture, because the copper(II) sulfate is not chemically joined to the water and can be separated again.
BIt is a compound, because it contains two substances.
CIt is an element, because it is one uniform colour.
DIt is a pure substance, because it looks the same throughout.
(c)
Explain, in terms of particles, why the crystals disappear when they are stirred into water.
[2 marks]
Total for question 5: 4 marks
6
A metalworker in Bangkok melts a sample of pure tin and lets it cool. She records its temperature every 30 seconds. The temperature falls steadily from 300 °C to 232 °C, stays at 232 °C for several minutes while the tin changes state, and then falls steadily again.
(a)
What is happening to the tin particles while the temperature stays at 232 °C?
[1 mark]
AThey stop vibrating.
BThey move faster and faster.
CThey move far apart to form a gas.
DForces between them pull them into fixed positions as the liquid becomes a solid.
(b)
What is the change of state of the tin while the temperature stays at 232 °C?
[1 mark]
AMelting
BFreezing
CCondensing
DEvaporating
(c)
A second sample of tin contains small amounts of lead mixed into it. Predict how its cooling curve would differ from the first sample's, and give a reason.
[2 marks]
Total for question 6: 4 marks
7
A forensic scientist in Johannesburg uses paper chromatography to find out which of two pens wrote a threatening note. She draws a pencil baseline 1.0 cm from the bottom of the paper, puts a small spot of ink from the note and from each pen on the line, and stands the paper in a beaker of solvent. When the solvent front has moved 8.0 cm above the baseline she removes the paper. The ink from the note forms three spots, at 2.0 cm, 4.8 cm and 6.4 cm above the baseline. Pen 1 also forms three spots, at 2.0 cm, 4.8 cm and 6.4 cm. Pen 2 forms two spots, at 3.2 cm and 6.4 cm.
(a)
Calculate the Rf value of the middle spot from the note. State what the number of spots shows about the ink in the note.
[3 marks]
(b)
Explain why the baseline is drawn in pencil and why the solvent must start below the baseline. Use the results to decide which pen wrote the note, giving two reasons.
[4 marks]
Total for question 7: 7 marks
8
A student in Pune separates a mixture of 50 cm³ of ethanol and 50 cm³ of water by fractional distillation, using a fractionating column with a thermometer at the top. She heats the flask gently and records the temperature. It rises to 78 °C and stays between 78 °C and 80 °C while 40 cm³ of liquid collects in the first beaker. It then rises quickly to 100 °C and stays there while the rest of the liquid collects in a second beaker. The boiling point of pure ethanol is 78 °C and of pure water is 100 °C. Ethanol is flammable.
(a)
Plan an investigation to test the hypothesis that fractional distillation separates ethanol and water better than simple distillation (with no fractionating column). In your answer, state a hypothesis with a scientific reason, identify the variables, and describe a safe method.
[6 marks]
(b)
Evaluate how successful the student's separation was, using the data, and suggest two improvements to her method. Finish with a justified conclusion.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).