OCR GCSE Combined Science A (Gateway) Chemistry Paper 9 Higher June 2022 question paper J250/09

A molecule of glucose has the molecular formula C₆H₁₂O₆.

What is the empirical formula of glucose?

A CHO

B CH₂O

C C₆H₁₂O₆

D (CO)₆H₁₂

The equation shows the reaction between carbon dioxide, CO₂, and hydrogen, H₂.

What has been reduced in this reaction?

A CO

B CO₂

C H₂

D H₂O

Which statement describes the isotopes of an element?

A Atoms that have different numbers of protons but the same number of electrons.

B Atoms that have different numbers of protons but the same number of neutrons.

C Atoms that have the same number of protons but different numbers of electrons.

D Atoms that have the same number of protons but different numbers of neutrons.

Which substance is an example of a formulation ?

A A macromolecule

B A metal

C An alloy

D An ionic compound

The diagram shows a chromatogram produced by paper chromatography.

What is the R_f value?

A –10

B –5

C 0.67

D 1.5

The table shows some information about four different acids.

Which acid is a dilute solution of a strong acid?

The ionic equation shows the reaction of chlorine, Cl₂, with sodium bromide, NaBr.

What is the simplest ionic equation for this reaction?

A solution has a pH of 3.

The solution is diluted with water by a factor of 1000.

What is the pH of the solution after dilution?

A 2

B 4

C 5

D 6

Fullerenes are allotropes of carbon that have many uses.

Fig. 11.1 shows a molecule of a fullerene.

Fig. 11.1

Which group of allotropes contain this fullerene?

Tick one (✓) box.

The carbon atoms in fullerenes are joined by covalent bonds.

Explain how two atoms of carbon form a covalent bond.

How many covalent bonds does one atom of carbon form in a molecule of fullerene, as shown in Fig. 11.1 ?

The model used to show the molecule of fullerene in Fig. 11.1 has limitations.

The table shows some statements about the model.

Which statements about this model are true, and which are false ?

Tick one (✓) box in each row.

Fullerenes can be used as lubricants. Lubricants reduce the friction between moving parts.

Fig. 11.2 shows a lubricant being sprayed onto the chain of a motorbike.

Fig. 11.2

Explain why fullerenes can be used as lubricants.

Use ideas about the structure and bonding of the fullerene shown in Fig. 11.1 in your answer.

A lubricant may need to be used at high temperatures.

Explain why fullerenes can be used at high temperatures.

Use ideas about the structure and bonding of the fullerene shown in Fig. 11.1 in your answer.

Potassium chloride, KC l, is an ionic compound.

It is made from potassium ions, K +, and chloride ions, C l –.

Explain why potassium is found in Group 1 of the Periodic Table.

Use ideas about the arrangement of electrons in an atom of potassium.

Explain how an atom of potassium reacts with an atom of chlorine to make potassium chloride.

A student electrolyses potassium chloride.

The diagram shows the equipment they use.

Describe and explain two ways the student could change the experiment to make it work.

In the successful electrolysis of potassium chloride, potassium is made at the cathode.

Explain how potassium atoms are made from potassium ions.

13* Hydrogen can form compounds with the Group 7 elements. These compounds are simple covalent molecules.

For example,

When simple covalent molecules are heated, they thermally decompose back into their elements.

For example,

Tables 13.1 and 13.2 show information about the compounds formed from hydrogen and some Group 7 elements.

Table 13.1

Table 13.2

Describe the trends in the properties of the compounds in Table 13.1.

Explain these trends using information from Table 13.2 and ideas about the structure and bonding of simple covalent molecules.

Calcium is a metal found in Group 2 of the Periodic Table.

Draw the arrangement of electrons in an atom of calcium.

Calcium is a metal which can conduct electricity.

Describe the structure and bonding in a metal and explain why metals can conduct electricity.

You can include a diagram in your answer.

Calcium reacts with water to form a solution of calcium hydroxide, Ca(OH)₂, and hydrogen.

Write the balanced symbol equation for the reaction of calcium with water.

Include state symbols in your equation.

A solution of calcium hydroxide is also called limewater.

Name the gas limewater is used as a test for.

Calculate the number of moles in 1.88 g of calcium hydroxide.

Give your answer to 2 significant figures.

Relative atomic mass (A_r): H = 1.0 O = 16.0 Ca = 40.1

Use your answer to part (d)(i) to calculate the concentration of calcium hydroxide in the solution formed.

Give your answer in mol / dm³.

Concentration of solution =........ mol / dm³

A student adds an excess of dilute hydrochloric acid, HC l, to a solution of calcium hydroxide, Ca(OH)₂.

Write the balanced ionic equation for the reaction of dilute hydrochloric acid and a solution of calcium hydroxide.

Describe and explain how the pH of the solution of calcium hydroxide changes as the dilute hydrochloric acid is added until it is in excess.

Colour changes can be used to show that oxidation and reduction happen in chemical reactions.

The diagram shows the reaction between an acidic solution of vanadium(IV) oxide and zinc.

• As the reaction happens the colour of the solution turns from blue to green.

The balanced half equation shows the reaction of vanadium(IV) oxide.

A student thinks that the half equation shows that reduction has taken place.

Describe two ways in which the half equation shows the student is correct.

This half equation shows the reaction of the zinc.

Complete the half equation for the reaction.

The student removes the zinc from the green solution by filtration. When they add some nitric acid to this solution it turns back from green to blue.

What is the role of the dilute nitric acid in this reaction?

Tick one (✓) box.