oxford cambridge and rsa gcse (9–1) combined science...

Turn over© OCR 2017 Practice paperDC (NF/SW) 153346/1

Oxford Cambridge and RSA

GCSE (9–1) Combined Science A(Gateway Science)J250/03/09 ChemistryFoundation and Higher Tier

Year 10 TestTime allowed: 1 hour 10 minutes

You must have:• a ruler (cm/mm)• the Data Sheet

You may use:• a scientific calculator

OCR is an exempt Charity

INSTRUCTIONS• Use black ink. You may use an HB pencil for graphs and diagrams.• Complete the boxes above with your name, centre number and candidate number.• Answer all the questions.• Write your answer to each question in the space provided.• Additional paper may be used if required but you must clearly show your candidate

number, centre number and question number(s).• Do not write in the barcodes.

INFORMATION• The total mark for this paper is 60.• The marks for each question are shown in brackets [ ].• Quality of extended response will be assessed in questions marked with an asterisk (*)• This document consists of 20 pages.

Last name

First name

Candidatenumber

Centrenumber

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J250/03© OCR 2017 Practice paper

SECTION A – FoundationAnswer all the questions.

1 A student tests a gas.

The gas turns limewater cloudy.

What is the name of the gas?

A carbon dioxide

B chlorine

C hydrogen

D oxygen

Your answer [1]

2 Elements in the Periodic Table are metals or non-metals.

Which of the elements is a non-metal?

A caesium

B calcium

C magnesium

D phosphorus

Your answer [1]

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J250/03 Turn over© OCR 2017 Practice paper

3 The electron arrangement for an element is 2, 8, 6.

In which group of the Periodic Table is this element found?

A 2

B 3

C 6

D 8

Your answer [1]

4 Sodium sulfate contains sodium ions, Na+, and sulfate ions, SO42−.

What is the formula for sodium sulfate?

A NaSO4

B Na(SO4)2

C Na2SO4

D Na2(SO4)2

Your answer [1]

4


5 Look at this reaction profile.

product

reactants

energy

progress of reaction

A

B C

D

Which letter shows the activation energy?

Your answer [1]

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SECTION B – Foundation

6 Iodine, I2, is a solid at room temperature and pressure.

(a) Describe the motion and arrangement of iodine molecules in solid iodine.

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(b) When solid iodine is heated it changes directly into a gas.

Describe the motion and arrangement of iodine molecules in iodine gas.

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(c) Iodine, I2, reacts with hydrogen to make hydrogen iodide, HI.

(i) Write the balanced symbol equation for this reaction.

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(ii) This reaction is a chemical change.

What is meant by a chemical change?

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7 A student investigates the electrolysis of copper sulfate solution using inert electrodes.

Look at the apparatus that she uses.

anodecathode

copper sulfate solution

dc supply– +

(a) Copper sulfate solution contains these particles.

Cu2+ H2O OH− H+ SO42−

Which two particles are attracted to the cathode?

.......................... and .......................... [1]

(b) What is meant by an inert electrode?

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(c) The student does the electrolysis five times.

• She does the experiment for 2, 4, 6, 8 and 10 minutes• She measures the mass of copper made each time.

Look at the graph of her results.

00

0.1

0.2

0.3

0.4

0.5

2 4 6time (minutes)

mass ofcopper (g)

8 10

(i) Draw a line of best fit. [1]

(ii) Use your line of best fit to calculate the rate that copper is made in grams per minute.

answer: ........................................ g/mins [2]

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8 A student investigates the law of conservation of mass.

Look at the apparatus he uses.

before mixing

thread

bariumchloridesolution

after mixing

thread

magnesium chloridesolution and solidbarium sulfate

magnesiumsulfatesolution

He records the total mass of the flask, test tube and contents before mixing.

This mass is 124.51 g.

The student tips the flask to let the two solutions mix.

He then records the total mass of the flask, test tube and its contents again.

(a) A reaction happens when the solutions are mixed.

Look at the equation for the reaction.

BaCl2(aq) + MgSO4(aq) MgCl2(aq) + BaSO4(s)

(i) Write the word equation for this reaction.

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..................................................................................................................................... [1]

(ii) What is the meaning of (aq) in the formula BaCl2(aq)?

..................................................................................................................................... [1]

(b) Predict the total mass of the flask, test tube and its contents after mixing.

mass = ................. g [1]

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(c) Complete the table of relative formula masses.

Use the space under the table for your working out.

Substance Relative formula mass

BaCl2 208.3

MgSO4

MgCl2

BaSO4 233.4

[2]

(d) Use the relative formula masses and the symbol equation to show if mass is conserved during this reaction.

[2]

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9* Tracy is separating a mixture of three substances A, B and C.

Look at the table. It gives information about these substances.

Substance Melting point(°C)

Boiling point(°C) Solubility in water

A 0 100 soluble

B –114 78.5 soluble

C 110 decomposes (breaks down) insoluble

Suggest how Tracy can separate the mixture to get pure samples of substances A, B and C.

Explain in detail how each method works.

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SECTION C – Higher

10 Graphite is an allotrope of the element carbon.

It is made up of layers of carbon atoms.

What type of bonds are present in the layers of carbon atoms in graphite?

A covalent

B ionic

C intermolecular

D metallic

Your answer [1]

11 Which statement best describes the structure of an atom?

A A nucleus containing protons and electrons, surrounded by neutrons.

B A nucleus containing neutrons and electrons, surrounded by protons.

C A nucleus containing protons and neutrons, surrounded by electrons.

D A nucleus containing neutrons, surrounded by electrons and protons.

Your answer [1]

12


12 The formula of ammonium sulfate is (NH4)2SO4.

What is the relative formula mass, Mr, of ammonium sulfate?

A 63.1

B 114.1

C 132.1

D 216.1

Your answer [1]

13 Lead nitrate solution, Pb(NO3)2(aq), reacts with sodium iodide solution, NaI (aq), to form a precipitate of lead iodide.

Which equation is the correct balanced ionic equation for this reaction?

A Pb2+(aq) + I2–(aq) PbI(s)

B Pb2+(aq) + 2I–(aq) PbI2(s)

C Pb2+(aq) + 2I–(aq) PbI2(aq)

D Pb+(aq) + I–(aq) PbI(s)

Your answer [1]

14 Hydrochloric acid is a strong acid.

Its pH is 0.22 at a concentration of 0.60 mol/dm³.

What is the pH at a concentration of 0.06 mol/dm³?

A –0.78

B 0.022

C 1.22

D 2.20

Your answer [1]

13


SECTION D – Higher

15 This question is about separation techniques.

(a) A student wants to find out which substances are present in two mixtures, M1, and M2.

He makes a chromatogram of the two mixtures.

He also makes a chromatogram of some substances he thinks may be in the mixtures.

Look at the chromatogram from the experiments.

M1 M2 A

unknownmixtures

M1 and M2

known singlesubstancesA, B and C

B C

solvent front

(i) Calculate the Rf values for B and for the first spot in mixture M2.

Use a ruler to help you.

Write your answers to two significant figures.

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..................................................................................................................................... [2]

(ii) Use your answers to part (i) to explain whether mixture M2 contains substance B.

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(b) The student concludes that mixture M1 contains substance A.

What other conclusion can he make from the chromatogram of mixture M1?

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............................................................................................................................................. [1]

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16 This question is about atomic structure.

(a) A scientist called J.J. Thomson suggested that atoms are spheres of positive charge with electrons dotted around inside.

This was called the ‘plum-pudding’ model.

Two scientists, Geiger & Marsden, did experiments to test the plum-pudding model.

They directed beams of positively charged alpha (α) particles at thin gold foil.

Look at the diagram of their results.

incident α particles

target foil

atom nucleus

Their results showed that:

▪ most of the particles went straight through the foil

▪ some of them were deflected from their path.

Describe what these observations showed about the structure of the atom.

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............................................................................................................................................. [2]

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(b) Complete the table to show the relative charge and relative mass of each particle.

Particle Relative charge Relative mass

Proton

Neutron

Electron

[2]

(c) Iron has an atomic number of 26.

Calculate the mean mass of an atom of iron.

Give your answer to three significant figures.

(Avogadro constant = 6.022 × 1023 atoms per mole).

Mean mass = ............................. g [2]

16


17* An oxygen isotope can be shown as

188O

Describe what can be deduced from this information about the structure of this oxygen isotope and the position of oxygen in the Periodic Table.

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18 A student is making zinc chloride.

(a) Look at the method he uses.

1. Measure 50 cm3 of dilute hydrochloric acid into a beaker.

2. Add a 1 cm piece of zinc metal.

3. Heat the mixture until crystals of zinc chloride are made.

The method does not make a pure dry sample of zinc chloride.

Write about the improvements that the student should make so that:

▪ the reaction is complete

▪ pure, dry zinc chloride can be separated from the reactants.

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............................................................................................................................................. [2]

(b) Zinc reacts with chlorine to form zinc chloride.

Zn + Cl2 ZnCl2

(i) Explain, in terms of electrons, which substance is oxidised in this reaction.

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..................................................................................................................................... [2]

(ii) Construct a balanced ionic equation to show the change that happens to zinc.

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18


19 A student adds 50 cm3 of 0.10 mol/dm3 sodium hydroxide solution, 5 cm3 at a time, to 25 cm3 of ethanoic acid.

She measures the pH of the mixture after she has added each 5 cm3. She plots a pH curve.

Look at her graph.

00123456789

1011121314

5 10 15 20 25 30volume of sodium hydroxide (cm3)

pH of mixture

35 40 45 50

(a) Explain, in terms of the hydrogen ion concentration, why the pH increases from 3 to 6.

............................................................................................................................................. [1]

(b) The student uses 0.10 mol/dm3 ethanoic acid in her experiment.

0.10 mol/dm3 is a dilute solution.

Ethanoic acid is a weak acid.

Explain the terms dilute and weak in relation to 0.10 mol/dm³ ethanoic acid.

dilute .........................................................................................................................................

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weak .........................................................................................................................................

............................................................................................................................................. [2]

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BLANK PAGE

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