OCR GCSE Combined Science A (Gateway) Chemistry Paper 4 Foundation June 2019 question paper J250/04

How does a catalyst speed up a reaction?

A It decreases the activation energy.

B It decreases the energy of the reactant particles.

C It increases the activation energy.

D It increases the energy of the reactant particles.

Which process leads to the greenhouse effect?

A Radiation absorbed by carbon dioxide

B Radiation causing plants to grow

C Radiation causing pollution

D Radiation damaging the ozone layer

Which graph shows the correct percentages of the three main gases in the atmosphere today?

This is part of the reactivity series.

Lead

Copper

Silver
less reactive

Which statement is correct?

A Copper can displace tin from tin chloride.

B Lead can displace copper from copper chloride.

C Lead can displace tin from tin chloride.

D Silver can displace copper from copper chloride.

A teacher adds calcium carbonate to an acid in four separate flasks, A, B, C and D.

He measures the time it takes for the same volume of carbon dioxide to be produced in each flask.

This is a graph of his results.

Which flask has the fastest rate of reaction?

Aluminium is extracted from aluminium oxide using electrolysis.

Carbon cannot be used to do this.

Why is electrolysis used?

A Aluminium is more reactive than carbon.

B Aluminium oxide dissolves in water.

C Aluminium oxide has a high melting point.

D Electrolysis uses less energy than extraction with carbon_.

Some metals react faster with an acid than others.

Which statement explains why?

A The acid gives off hydrogen atoms more easily.

B The acid gives off hydrogen gas more easily.

C The metal forms a negative ion more easily.

D The metal forms a positive ion more easily.

The elements neon and argon in Group 0 are unreactive.

Which statement explains why?

A These elements have 8 electrons in the nucleus.

B These elements have 8 electrons in the outer shell.

C These elements have 8 protons in the nucleus.

D These elements have 8 protons in the outer shell.

This question is about Group 1 and Group 7 elements.

A Group 1 element D reacts with water.

This is the equation:

Name element D.

A teacher shows this reaction to his class.

Describe one safety precaution he should use.

E is a colourless gas.

How can you show if the gas is hydrogen or oxygen?

Describe the tests for hydrogen and oxygen, and the results you would expect with gas E.

test for hydrogen........

result with gas E........

result with gas E........

Group 1 elements are very reactive.

Write down the reason why.

Table 11.1 shows the densities of the first four Group 1 elements at room temperature_.

Calculate how many times larger the density of rubidium is than the density of lithium

Give your answer to 1 significant figure.

1 g of sodium and 1 g of potassium are mixed to form an alloy.

Calculate the density of the alloy.

Density =........ g / cm³

The element caesium (Cs) is also in Group 1. Caesium is found below rubidium in the Periodic Table.

Use the information in Table 11.1 and your knowledge of trends in properties for Group 1 elements to estimate the density of caesium.

Density of caesium =........ g / cm³

A student reacts a solution of KBr with chlorine, Cl₂.

Balance the equation for this reaction.

What is the name of the chemical KBr?

Tick (✓) one box.

What does the reaction tell you about the reactivity of Br₂ and Cl₂?

Explain your answer.

The reaction between sulfur dioxide and oxygen is reversible.

In a closed system the reaction between sulfur dioxide and oxygen reaches a dynamic equilibrium.

Use a symbol from the list to complete the sentence.

At equilibrium, the rate of the forward reaction is …….... the rate of the reverse reaction.

What is meant by the term reversible reaction ?

Name one source of sulfur dioxide in the atmosphere.

Describe two problems caused by the release of sulfur dioxide into the atmosphere.

The table shows some relative atomic masses.

Calculate the percentage, by mass, of oxygen in SO₂.

Give your answer to 1 decimal place.

The amount of sulfur dioxide released in the UK is decreasing.

This graph shows how it has decreased since 1970.

How much did the sulfur dioxide decrease between 1975 and 2015?

Sulfur dioxide decrease =........ kilotonnes

One homologous series of organic compounds is called the alkanes.

They have the general formula C_nH_2n+2.

The alkane with one carbon atom, n = 1, is called methane.

Write down the formula of methane.

Table 13.1 shows the energy released when some alkanes burn in oxygen.

Plot a graph of number of carbon atoms against energy released using the data in Table 13.1 and draw a line of best fit.

Use the graph to predict the energy released when methane burns (1 carbon atom).

Energy released =........ kJ / mol

Hexane is a liquid alkane that burns in oxygen.

Which element in hexane is oxidised to produce water?

Give a reason for your answer.

A student burns 10.0 g of hexane.

These are his results.

Mass of hexane before burning = 10.0 g Mass of hexane after burning = 0.0 g

The law of conservation of mass is true for this reaction.

Explain why.

Local councils collect waste from households.

The graph shows what happened to the waste between 2001 and 2017.

Key

Describe and explain one trend shown by the graph.

State one disadvantage of recycling.

A student adds some magnesium to dilute hydrochloric acid (HC l).

Magnesium chloride (MgCl₂) and hydrogen gas is formed.

Write a balanced symbol equation for this reaction.

Identify the independent variable in the investigation.

Identify two control variables in the investigation.

The results at 0.75 mol / dm³ are repeated. (d)

This is a graph of the student’s results.

Concentration of acid (mol / dm³)

What conclusion can you make from these results?

Include ideas about particles in your answer.