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 was released during the Great Oxidation Period from extensive volcanic activity

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

#2. 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, there is more surface where collisions can take place

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

#3. How did the oceans form?

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

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

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

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

Select all that apply:

alpha particle treatment

ozonation

chlorination

UV treatment

#6. 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

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

The speed at which reactants are turned into products

The number of particles involved in a reaction in 1 minute

The rate of temperature change in the surroundings

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

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

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

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

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

It will decrease

It will increase

It will stay the same

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

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

It provides the activation energy needed

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

#11. 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, oxygen and water vapour

Carbon dioxide, methane and water vapour

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

Select all that apply:

Planting trees

Burning fossil fuels

Livestock farming

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

distilled water is cheaper than tap water

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

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

#14. 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

#15. 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

#16. 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

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

No

Sometimes

Yes

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

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

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

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

#19. 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?

PR energy

The Introactive energy minimum

Activation energy

Reactionary energy

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

Select all that apply:

Using renewable energies instead of fossil fuels

Cutting down forests to give humans a new place to live

Building flood defences

Ensuring clean water supplies for vulnerable communities

Carbon capture from the atmosphere and storage underground

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

#21. 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.

Visible/infrared waves, infrared waves

Gravitational waves, ultraviolet waves

Sound waves, ocean waves

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

Select all that apply:

distillation

reverse osmosis

filtration

#23. Which of these is a fast reaction?

Photosynthesis

Explosions

Rusting

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

Select all that apply:

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

Rising ocean temperatures causing coral bleaching and other adverse effects

Extinctions of species unable to migrate or adapt to higher temperatures

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

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

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

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

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

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

#26. 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 temperature throughout a reaction

By measuring the changes in volume of reactants and products

By measuring the changes in mass of reactants and products

#27. 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

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

Select all that apply:

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

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

Very small changes are difficult to accurately measure

#29. 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 increases

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

As temperature increases, rate of reaction decreases

#30. 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 reactants of the reaction

The concentration of the products of the reaction

The mass of the products of the reaction

The volume of the products of the reaction

The volume of the reactants of the reaction

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

demicronation

desalination

unsaturation

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

Earthquakes

Volcanism

Glaciation

Continental drift

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

No, even if reactants have not run out

Yes, until reactants run out

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

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

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

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

#35. 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

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

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

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

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

Select all that apply:

seawater

aquifers

rivers

lakes

#38. 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

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

No, even if there are still reactants

Yes, until reactants run out

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

No

Yes

#41. 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:

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

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

Oxygen is not produced by volcanoes

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

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

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

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

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

#3. How did the oceans form?

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

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

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

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

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

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

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

#11. 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.

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

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

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

#15. 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?

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

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

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

#19. 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?

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

#21. 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.

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

#23. Which of these is a fast reaction?

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

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

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

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

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

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

#30. 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?

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

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

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

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

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

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

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

#38. 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?

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

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

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

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

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