The composition & evolution of the atmosphere

Which gas made up the greatest proportion of the Earth’s early atmosphere?

Figure 4 shows the composition by volume of the Earth’s atmosphere today.

Give the name of the gas in Earth’s atmosphere today that makes up the largest proportion.

Using the information in Figure 4, calculate the percentage of argon and other gases in the Earth’s atmosphere today.

The percentage of oxygen in air can be measured using the apparatus shown in Figure 5.

The oxygen in the air reacts with the heated zinc.

Explain one change that would be seen during the reaction.

Name the product formed when the zinc reacts with oxygen in this experiment.

Figure 6 shows the electron configuration of an argon atom.

State why argon is unreactive.

Argon makes up 0.93% of the Earth’s atmosphere today.

Calculate the volume of argon, in cm³, in 4000 cm³ of air.

This question is about the atmosphere.

Describe the test to show that a gas is oxygen.

Copper reacts with oxygen to form copper oxide.

2.100 g of copper will react completely with 0.529 g of oxygen.

In an experiment, 4.200 g of copper is heated with 50.000 g of oxygen until the reaction is complete.

Calculate the mass of oxygen remaining at the end of the experiment.

mass of oxygen =_........ g

Helium, neon and argon are all inert.

Explain, in terms of electrons, why these gases are inert.

Two pieces of steel can be joined by heating the metal pieces with a very hot flame.

This process is often carried out in an argon atmosphere rather than in air.

Which property makes argon gas suitable for this use?

*(d) Figure 10 shows how plant life and the atmosphere of Earth have changed over time.

Explain the effect that plant life has had on the Earth’s atmosphere and the temperature of the Earth.

You should refer to the information in Figure 10 including

• the plant life

• the amounts of carbon dioxide

• the amounts of oxygen

A scientist produced the information in Figure 6 about the Earth’s atmosphere and the Earth’s average surface temperature.

Use words from the box to complete the following sentence.

Over the past 3 billion years the average surface temperature of the Earth

The Earth’s atmosphere 3 billion years ago contained much more water vapour than today’s atmosphere.

Explain what happened to the water vapour.

Scientists think that the decrease in percentage of carbon dioxide was partly due to this gas being used in the growth of primitive plants.

Carbon dioxide was used in the growth of primitive plants and produced oxygen.

Give the name of the process in plants that takes in carbon dioxide and produces oxygen.

Which of the following tests would show that a gas is oxygen?

Many people are concerned by the increasing amount of carbon dioxide in the atmosphere.

The amount of carbon dioxide in the atmosphere is measured in parts per million (ppm).

Figure 7 shows the amount of carbon dioxide in the atmosphere in June 2001 and in June 2021.

Calculate the increase in the amount of carbon dioxide, in ppm, from June 2001 to June 2021.

Give your answer to the nearest whole number.

increase in amount of carbon dioxide =_........ ppm

State one possible effect that could be caused by the increasing amount of carbon dioxide in the atmosphere.

Figure 5 shows the percentage of three gases, X, Y and Z, in the Earth’s early atmosphere.

What is the name of gas Z ?

It is thought that small quantities of hydrogen sulfide, H₂S, were also in the Earth’s early atmosphere.

Draw the dot and cross diagram for a molecule of hydrogen sulfide.

Show outer electrons only.

Acid rain is caused by some pollutant gases present in the atmosphere.

Explain how impurities in fossil fuels can result in acid rain.

A student investigates the effect of acid rain on cress plants.

The student uses this method.

step 1 grow 20 cress plants in each of two dishes, A and B

step 2 water the cress plants in dish A with 10 cm³ of dilute hydrochloric acid with a pH of 2

step 3water the cress plants in dish B with 10 cm³ of pure water with a pH of 7

step 4 repeat steps 2 and 3 every day for one week

step 5 count how many plants are still alive after one week.

State what piece of equipment the student could use to measure the pH of each liquid.

Explain one improvement that the student could make to the method to make the results more valid.

This question is about gases.

When sodium is added to water, hydrogen gas is produced.

Which observation shows that a gas has been produced?

Some damp litmus paper is placed in a gas. The litmus paper is bleached.

Which gas bleaches damp litmus paper?

When calcium carbonate is heated it decomposes.

When 5.000 g of calcium carbonate is heated, the mass of solid remaining is 2.800 g.

Calculate the mass of carbon dioxide that has been released.

Give your answer to three significant figures.

mass of carbon dioxide =_........ g

A diagram of an atom of helium is shown in Figure 9.

Explain, using Figure 9, why helium is inert.

Helium is used to fill balloons.

State one property of helium, apart from it being inert, that makes it suitable for filling balloons.

*(e) Figure 10 shows the relative amounts of three gases in the early atmosphere compared to the composition of today’s atmosphere.

Natural processes and human activities have altered the relative amounts of these gases in the atmosphere.

Explain how the relative amount of each of the gases in Figure 10 has increased or decreased over time.

This question is about oxygen.

The percentage of oxygen in today’s atmosphere is greater than the percentage of oxygen in the Earth’s early atmosphere.

Explain what caused this change to happen.

Magnesium reacts with oxygen from the air to form magnesium oxide.

A student carries out an investigation to determine the mass of magnesium oxide formed when a known mass of magnesium reacts completely with oxygen.

This is the method the student used.

step 1 find the mass of a crucible and lid

step 2 put a known mass of magnesium into the crucible and put the lid on

step 3 heat for five minutes using a roaring Bunsen burner flame

step 4 let the crucible, lid and contents cool down

step 5 find the final mass of the crucible, lid and contents

Explain how the student could check that the magnesium had reacted completely with oxygen.

In another experiment, it was found that 1.24 g of phosphorus reacted completely with 1.60 g of oxygen to form phosphorus oxide.

The relative formula mass of this phosphorus oxide is 284.

Deduce the molecular formula of this phosphorus oxide.

You must show your working.

(relative atomic masses: O = 16, P = 31)

molecular formula =_........

A student uses the apparatus shown in Figure 6 to investigate the percentage of oxygen in the atmosphere.

The apparatus was left for a few days.

Explain one change the student would see after a few days.

Explain one change that can be made to the apparatus in Figure 6 to allow the student to calculate the percentage of oxygen in the atmosphere.

The two most common gases in today’s atmosphere are nitrogen and oxygen.

What is the third most common gas in today’s atmosphere?

What is the percentage of oxygen in today’s atmosphere?

Give the name of the most common gas in the Earth’s early atmosphere.

This early atmosphere was hot and contained water vapour. The atmosphere today contains less water vapour.

Explain what caused the amount of water vapour in the atmosphere to decrease.

The concentration of carbon dioxide in the atmosphere can be measured in parts per million (ppm).

Figure 1 shows the measurements in January 2018 and January 2019.

Calculate the increase in the concentration, in ppm, of carbon dioxide from January 2018 to January 2019.

Give your answer to the nearest whole number.

increase in concentration of carbon dioxide =_........ ppm

Give a possible cause for this increase in the concentration of carbon dioxide.

Air contains several gaseous elements.

Which of these shows the three most common gaseous elements in air, listed in order from the most common to the least common?

The density of a gas can be found using the equation

A student carried out an experiment to find the density of argon.

The mass of a stopper and flask, containing no gas, was known. The flask was completely filled with argon and its mass measured.

Figure 2 shows the results the student wrote down.

Use the results to calculate the density of argon in g cm^–3.

density of argon =_........ g cm^–3

The flask used for the experiment is shown in Figure 3. The flask holds 250.0 cm³ when filled up to the line.

There is an error in the volume the student has used in the calculation. This would give an incorrect value for the density of argon.

Identify this error and state what should be done to correct it.

error_........

what should be done to correct it_........

Four of the noble gases are argon, helium, krypton and neon.

Give these gases in order of increasing density.

Much of the carbon dioxide present in the Earth’s early atmosphere dissolved into the oceans.

This led to the formation of compounds including calcium carbonate, CaCO₃.

Some of the calcium carbonate reacted with magnesium ions to form dolomite, CaMg(CO₃)₂.

Complete the ionic equation for the reaction of calcium carbonate with magnesium ions.

_........ CaCO₃ +_........ CaMg(CO₃)₂ + Ca²⁺ dolomite

P and Q are both mixtures of gases. One has the same composition as the early atmosphere and the other has the same composition as the current atmosphere.

Tests are carried out on gas mixtures P and Q.

The test for carbon dioxide is to bubble the gas into limewater; if carbon dioxide is present calcium carbonate is formed.

The results of the tests are shown in Figure 4.

Explain, using the data in Figure 4, which gas mixture represents the early atmosphere.

Plants release oxygen into the atmosphere.

What is the name of the process that releases oxygen into the atmosphere?

The atmosphere contains 21% of oxygen.

Figure 1 shows an incomplete bar chart of the main gases in the atmosphere.

Complete the bar chart by showing the percentage of oxygen in the atmosphere.

Calculate the volume of oxygen present in 300 cm³ of air.

(volumes are measured under the same conditions of temperature and pressure)

volume of oxygen =_........ cm³

An atom of an element has an atomic number and a mass number.

Draw one straight line from each of these to the numbers of subatomic particles it shows to be present in an atom.

number of subatomic particles in an atom

Which test shows a gas is oxygen?

Carbon dioxide is one of the gases in the Earth’s atmosphere. The percentage of carbon dioxide in the Earth’s atmosphere has changed over time.

Which row of the table shows the approximate percentage of carbon dioxide thought to be in the Earth’s early atmosphere and how this percentage changed to form the Earth’s atmosphere today?

The actual percentage of carbon dioxide in the Earth’s atmosphere today varies.

Explain two factors that cause the percentage of carbon dioxide in today’s atmosphere to vary.

factor 1_........

Carbon dioxide is a simple molecular, covalent compound.

It has a low boiling point of –78.5C.

Explain why carbon dioxide has a low boiling point.

Calculate the number of molecules in 0.11 g of carbon dioxide.

Give your answer to two significant figures.

(relative formula mass: CO₂ = 44 Avogadro constant = 6.0210²³)

number of molecules =_........

Figure 5 shows one molecule of each of four different substances, A, B, C and D.

substance A substance B substance C substance D

Figure 5

State the formula of a molecule of substance B.

Substance C can be formed by burning an element in oxygen.

Write the word equation for this reaction.

Consider substances A, B, and D.

Give the letters of the two substances that can be formed by burning an element in oxygen.

The amount of oxygen in the atmosphere has increased since the Earth’s early atmosphere was formed.

Explain what has caused this change.

Figure 6 shows a graph of the amount of carbon dioxide in the Earth’s atmosphere from 1985 to 2005.

Describe how the amount of carbon dioxide in the Earth’s atmosphere varies within each year.

Describe the overall trend in the amount of carbon dioxide in the Earth’s atmosphere from 1985 to 2005.

Calculate the change in the amount of carbon dioxide in the Earth’s atmosphere from the beginning of 1990 to the beginning of 2000.

change in amount =_........ ppm

The Earth’s atmosphere contains several gases.

Figure 1 shows the relative amounts of gases thought to be in the Earth’s early atmosphere.

The amount of water vapour in today’s atmosphere is much less than the amount in the Earth’s early atmosphere.

Explain why the amount of water vapour in the atmosphere has decreased.

The apparatus shown in Figure 2 is used to find the percentage of oxygen in dry air.

Syringe A contains 50 cm³ of dry air and syringe B contains no air. The copper in the glass tube is heated strongly. The air in the apparatus is passed backwards and forwards over the copper until all the oxygen has been removed.

The following results were obtained

initial volume of air in apparatus = 50 cm³

final volume of gas in apparatus = 40 cm³

Calculate the percentage of oxygen in this sample of dry air.

percentage oxygen in the air =_........

At the end of the experiment, the apparatus and its contents are allowed to cool before the final volume of gas is measured.

The apparatus and its contents must be allowed to cool because

The Earth’s earliest rocks contained iron sulfide and no iron oxide. Later the rocks contained iron oxide as well as iron sulfide.

Explain what happened to allow this change to occur.