GCSE OCR Chemistry A Papers 2 and 4 Automarked

#1. Why did the amount of oxygen in the atmosphere increase over time?

Plants and other organisms began to perform photosynthesis, producing oxygen gas

Oxygen present in the Earth's mantle, seeped out over time and escaped via deep ocean ridges

Oxygen was released during the Great Oxidation Period from extensive volcanic activity

#2. Which of the following are commonly used as methods of sterilising fresh water? ? 3

Select all that apply:

ozonation

chlorination

alpha particle treatment

UV treatment

#3. Which of these is a fast reaction?

Rusting

Photosynthesis

Explosions

#4. Which of the following is the chemical test for oxygen?

A glowing splint is relit in a test tube filled with oxygen

An audible squeaky pop is heard when a lit splint is exposed to a test tube full of oxygen

Oxygen is bubbled through limewater and it turns cloudy when oxygen is present

#5. Which human activities cause increases in the greenhouse gases – carbon dioxide and methane?

Select all that apply:

Burning fossil fuels

Livestock farming

Planting trees

#6. Will endothermic reactions continue if there is no energy input?

Yes, until reactants run out

No, even if there are still reactants

#7. Which of the following are problems that would arise from measuring an extremely slow rate of reaction?

Select all that apply:

Extremely slow reactions do not always follow the law of conservation of energy

Very slow changes require long-term experiments - costly and may exceed human lifetimes

Very small changes are difficult to accurately measure

#8. Greenhouse effect 2) Fill in the blanks: Greenhouse gases such as ……….. , …………. and ……….. absorb infrared radiation from the Earth and re-emit it back to the Earth’s surface, causing warming.

Carbon dioxide, water vapour and nitrogen

Carbon dioxide, methane and water vapour

Carbon dioxide, oxygen and water vapour

#9. Chemical reactions require a high enough collision energy for reactions to take place. What do we call the minimum amount of energy needed for a reaction?

Activation energy

Reactionary energy

The Introactive energy minimum

PR energy

#10. What is the current composition of the Earth’s atmosphere?

78% nitrogen, 21% oxygen, 0.9% argon, and 0.1% other gases

78% carbon dioxide, 21% oxygen, 0.9% argon, and 0.1% other gases

78% oxygen, 21% nitrogen, 0.9% argon, and 0.1% other gases

#11. Which of these describes the term “rate of reaction”?

The speed at which reactants are turned into products

The rate of temperature change in the surroundings

The number of particles involved in a reaction in 1 minute

#12. Why did the concentration of carbon dioxide in the atmosphere decrease after the oceans formed?

Carbon dioxide dissolved into the oceans and sea organisms used carbon in their shells as calcium carbonate

Carbon dioxide escaped the atmosphere as the Earth's spin increased in speed, causing an increase the centrifugal force

Carbon dioxide was split by photolysis, producing pure carbon which rained down as a solid.

#13. Is it possible to control the rate of reaction?

Yes

No

#14. Which steps can we take to reduce the impact of climate change on humanity or prevent further climate change?

Select all that apply:

Building flood defences

Ensuring clean water supplies for vulnerable communities

Pumping water to the Sahara Desert and creating a new place to live

Cutting down forests to give humans a new place to live

Carbon capture from the atmosphere and storage underground

Using renewable energies instead of fossil fuels

#15. Which of the following examples matches the composition of Earth’s early atmosphere?

Mainly carbon dioxide, some water vapour, little or no oxygen and small amounts of other gases

Mainly water vapour, some oxygen, little or no carbon dioxide and small amounts of other gases

Mainly oxygen, some water vapour, little or no carbon dioxide and small amounts of other gases

#16. How could we accurately monitor the rate of a reaction? ? Three answers

Select all that apply:

By measuring the concentration of reactants and products throughout a reaction

By measuring the changes in mass of reactants and products

By measuring the temperature throughout a reaction

By measuring the changes in volume of reactants and products

#17. Iron is turned into iron oxide when exposed to the air. This is a process also known as rusting. Is the rate of reaction fast or slow in rusting?

Fast

Slow

#18. Why may our attempts to mitigate the effects of climate change cause further damage to the environment?

Unexpected consequences often follow when we interrupt complex systems that do not fully understand e.g. the atmosphere

Vulnerable ecosystems may be disrupted in our attempts to improve conditions for humans

Animals and plants will resist the efforts we take to help them causing distress and loss of ecological productivity

#19. What is the evidence supporting the idea that there was very little oxygen in the atmosphere in Earth’s early atmosphere?

Select all that apply:

Oxygen is not produced by volcanoes

The gravitational field strength of the Earth is not strong enough to hold oxygen in the atmosphere

No iron oxide bands in layers of rock are present in deeper (older) layers

#20. Temperature affects the rate of reaction. Which of the following is the correct description of what happens when temperature changes?

As temperature increases, rate of reaction decreases

Rate of reaction is highest at very high and very low temperatures

As temperature increases, rate of reaction increases

#21. What evidence supports the notion that human activities are contributing to climate change?

Gradual climate warming has occurred since the evolution of our species

Correlation between increases in atmospheric temperatures and historic releases of greenhouse gases, due to combustion of fossil fuels

#22. Which geological process formed Earth’s atmosphere?

Glaciation

Volcanism

Continental drift

Earthquakes

#23. Which of these reasons explains why temperature affects rate of reaction?

Reactant particles at higher temperatures move more quickly, collide more often and with enough energy to react

Reactant particles at lower temperatures are struck by rapidly moving electrons, causing the reaction to happen faster

Reactant particles are unaffected by temperature, but the bonds at higher temperatures become weaker leading to an increased rate of reaction

#24. Which processes can we use for purifying sea water?

Select all that apply:

filtration

reverse osmosis

distillation

#25. Greenhouse effect 1) Fill in the blanks: Energy from the sun in the form of …….. hits the Earth’s surface and ……. are emitted back towards the atmosphere.

Gravitational waves, ultraviolet waves

Visible/infrared waves, infrared waves

Sound waves, ocean waves

#26. How did the oceans form?

Liquid water gradually seeped directly out of the Earths crust, for thousands of years

Liquid water spontaneously formed when the ammonia and and methane in the atmosphere interacted chemically

Water vapour in the atmosphere condensed as the Earth cooled, forming the oceans

#27. On the early Earth, there was a lot of volcanic activity as the planet was cooling down. How can we link this to the formation of the atmosphere?

Measure the gases released by volcanoes and compare them to the composition of the atmosphere over time

Assume that volcanic activity is not relevant to the atmosphere and look for other sources of gases

#28. What is the name of the process by which salt is removed from water?

unsaturation

demicronation

desalination

#29. Fresh water contains many different contaminants and so must be cleaned before it becomes potable. Which is the correct treatment path?

water from source --> sedimentation tank --> filtration tower --> chlorine added --> storage --> water pumped to homes

water from source --> chlorine added --> filtration tower --> sedimentation tank --> storage --> water pumped to homes

water from source --> filtration tower --> chlorine added --> water pumped to homes

#30. Why is a spark often needed to start a combustion reaction?

It provides the activation energy needed

It removes excess nitrogen from the surrounding area, making ignition easier

It releases electrons from their shells and they rapidly ignite the fuel

#31. Which evidence provides information about carbon dioxide concentration and global temperatures?

Using the oldest continuous temperature measurements from humans and using computers to predict long term trends with this data

Ice cores which trap atmospheric gases when snow falls producing layers over time

#32. Which of the following are the main sources of drinking water in the UK?

Select all that apply:

aquifers

lakes

seawater

rivers

#33. Why is there a minimum energy required for reactions to occur?

High collision energies are more likely to break chemical bonds

High energies cause spontaneous rearrangement of particles without impacts between them

#34. Increasing the concentration of solutions increases the rate of reaction, why is this the case?

When solutions are more concentrated, the intermolecular forces become weaker and bonds are more easily broken

More collisions take place because there are more particles in the same volume

When solutions are dilute, there are more particles in the same volume

#35. Which of the following are effects of climate change?

Select all that apply:

Rising ocean temperatures causing coral bleaching and other adverse effects

Extinctions of species unable to migrate or adapt to higher temperatures

Lower pH of oceans due to dissolving carbon dioxide producing carbonic acid

More extreme weather events (stronger storms, rainfall and droughts)

Rising sea levels due to ice in the south pole and in glaciers melting

#36. Why do historical measurements by humans of global temperature have some uncertainty?

Select all that apply:

Early scientists were in competition to record the highest temperatures

Instruments to measure temperature were not very accurate in the past and have gained more resolution over time

The longest continuous record of temperature is only available in one place

#37. In an experiment to measure the rate of photosynthesis of pondweed in a test tube, the number of bubbles (oxygen) produced per minute is used to determine the rate of reaction. What is this experiment actually measuring?

The mass of the products of the reaction

The mass of the reactants of the reaction

The concentration of the products of the reaction

The volume of the reactants of the reaction

The volume of the products of the reaction

#38. When there are more frequent collisions between particles, what will happen to the rate of reaction?

It will stay the same

It will increase

It will decrease

#39. Will exothermic reactions continue if there is no energy input?

Yes, until reactants run out

No, even if reactants have not run out

#40. Does increasing the pressure of gases increase the rate of reaction?

Sometimes

No

Yes

#41. Surface area to volume ratio affects rate of reaction. Why is that the case?

With lower surface area to volume ratio, objects are much hotter and travel faster

With higher surface area to volume ratio, the overall temperature of reactants is lower, this leads to increased collision impact when struck

With higher surface area to volume ratio, there is more surface where collisions can take place

#42. Why do we use distilled water for chemical analysis?

distilled water is cheaper than tap water

distilled water is warmer so it is better for conducting chemical analysis

tap water contains small amounts of dissolved salts which could contaminate the results

GCSE OCR Chemistry A Papers 2 and 4

Good Luck!

Results

#1. Why did the amount of oxygen in the atmosphere increase over time?

#2. Which of the following are commonly used as methods of sterilising fresh water? ? 3

#3. Which of these is a fast reaction?

#4. Which of the following is the chemical test for oxygen?

#5. Which human activities cause increases in the greenhouse gases – carbon dioxide and methane?

#6. Will endothermic reactions continue if there is no energy input?

#7. Which of the following are problems that would arise from measuring an extremely slow rate of reaction?

#8. Greenhouse effect 2) Fill in the blanks: Greenhouse gases such as ……….. , …………. and ……….. absorb infrared radiation from the Earth and re-emit it back to the Earth’s surface, causing warming.

#9. Chemical reactions require a high enough collision energy for reactions to take place. What do we call the minimum amount of energy needed for a reaction?

#10. What is the current composition of the Earth’s atmosphere?

#11. Which of these describes the term “rate of reaction”?

#12. Why did the concentration of carbon dioxide in the atmosphere decrease after the oceans formed?

#13. Is it possible to control the rate of reaction?

#14. Which steps can we take to reduce the impact of climate change on humanity or prevent further climate change?

#15. Which of the following examples matches the composition of Earth’s early atmosphere?

#16. How could we accurately monitor the rate of a reaction? ? Three answers

#17. Iron is turned into iron oxide when exposed to the air. This is a process also known as rusting. Is the rate of reaction fast or slow in rusting?

#18. Why may our attempts to mitigate the effects of climate change cause further damage to the environment?

#19. What is the evidence supporting the idea that there was very little oxygen in the atmosphere in Earth’s early atmosphere?

#20. Temperature affects the rate of reaction. Which of the following is the correct description of what happens when temperature changes?

#21. What evidence supports the notion that human activities are contributing to climate change?

#22. Which geological process formed Earth’s atmosphere?

#23. Which of these reasons explains why temperature affects rate of reaction?

#24. Which processes can we use for purifying sea water?

#25. Greenhouse effect 1) Fill in the blanks: Energy from the sun in the form of …….. hits the Earth’s surface and ……. are emitted back towards the atmosphere.

#26. How did the oceans form?

#27. On the early Earth, there was a lot of volcanic activity as the planet was cooling down. How can we link this to the formation of the atmosphere?

#28. What is the name of the process by which salt is removed from water?

#29. Fresh water contains many different contaminants and so must be cleaned before it becomes potable. Which is the correct treatment path?

#30. Why is a spark often needed to start a combustion reaction?

#31. Which evidence provides information about carbon dioxide concentration and global temperatures?

#32. Which of the following are the main sources of drinking water in the UK?

#33. Why is there a minimum energy required for reactions to occur?

#34. Increasing the concentration of solutions increases the rate of reaction, why is this the case?

#35. Which of the following are effects of climate change?

#36. Why do historical measurements by humans of global temperature have some uncertainty?

#37. In an experiment to measure the rate of photosynthesis of pondweed in a test tube, the number of bubbles (oxygen) produced per minute is used to determine the rate of reaction. What is this experiment actually measuring?

#38. When there are more frequent collisions between particles, what will happen to the rate of reaction?

#39. Will exothermic reactions continue if there is no energy input?

#40. Does increasing the pressure of gases increase the rate of reaction?

#41. Surface area to volume ratio affects rate of reaction. Why is that the case?

#42. Why do we use distilled water for chemical analysis?

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