OCR GCSE Combined Science B (21st Century) Paper 2 June 2019 question paper

Lithium metal is a group 1 element. Lithium atoms have the electron arrangement 2.1.

Which of the following statements about the atoms of all group 1 elements are true and which are false ?

Tick (✓) one box in each row.

The elements on the left of the periodic table are all metals.

Which two statements about atoms of these elements are true ?

Tick (✓) two boxes.

How do the observations show the trend in reactivity going down Group 1 of the Periodic Table?

Many countries with sunny climates get most of their salt from seawater.

The seawater is trapped in shallow pools and left in the sun. After some time, piles of solid salt form.

Complete the sentences to explain how solid salt forms.

The heat / light from the sun decreases / increases the temperature in the shallow pools.

This causes the water / salt to evaporate / dissolve.

The piles of solid salt contain a mixture of salt and sand.

Sand is insoluble in water.

Jack plans an experiment to find the percentage of pure salt in the mixture. These are the steps he plans. They are not in the correct order.

A Add water to the mixture and stir.

B Collect a sample of the mixture.

C Filter and collect the solution.

D Heat the solution until all water has gone.

E Weigh the pure salt.

F Weigh the mixture.

Put the steps in the correct order.

Jack finds that his method makes very small crystals.

How could he change step D so that he makes larger crystals?

Jack used 10.0 g of the mixture for his sample.

He used a dish to weigh the pure salt he made.

Mass of empty dish = 50.0 g

Mass of dish with pure salt = 58.4 g

Calculate the mass of pure salt he made.

The percentage of pure salt in the mixture can be calculated using the formula:

Calculate the percentage of pure salt in the sample.

Graphite tennis rackets are made from a polymer combined with graphite fibres.

What is the name for a type of material that is made from two or more substances combined together?

ceramic composite metal plastic

A sample of PVC has a mass of 12.0 g and a volume of 8.0 cm³. (c)

Calculate the density of PVC.

Density =........ g / cm³

* A company decides to make a new tennis racket. They want the new racket to be stiff, light and strong.

The company considers using steel, aluminium alloy or graphite for the new racket.

Decide which of these three materials is the best choice for the racket by discussing their advantages and disadvantages.

Use data from the table to support your answer.

Mia adds magnesium to dilute hydrochloric acid.

Complete the word and balanced symbol equations for the reaction between magnesium and hydrochloric acid.

Mia measures the volume of hydrogen gas every 30 seconds.

Which piece of apparatus could she use to measure the volume of hydrogen collected?

balance beaker gas syringe pipette thermometer

She plots her results on a graph.

Which statement is the best description of what is happening during the first 12 s of the reaction in Fig. 4.1 ?

Tick (✓) one box.

Which statement is the best description of what is happening after 300 seconds in Fig. 4.1 ?

Tick (✓) one box.

Using Fig. 4.1, what is the total volume of hydrogen collected in this experiment?

Zinc is made by heating zinc oxide with carbon.

The zinc oxide is reduced by the carbon to make zinc.

What does reduced mean in this situation?

Tick (✓) one box.

Zinc can be made by heating zinc oxide with carbon.

Aluminium cannot be made by heating aluminium oxide with carbon.

Which two statements explain why?

Tick (✓) two boxes.

Aluminium is made by passing electricity through molten aluminium oxide.

What state is molten aluminium oxide in?

gas liquid solvent solution

Fig. 5.1 shows the ions in molten aluminium oxide.

(ii) Molten aluminium oxide conducts electricity. Solid aluminium oxide does not.

Explain why, using Fig. 5.1 to help you.

A positive and negative electrode are used to pass electricity through molten aluminium oxide. A product is made at each electrode.

Draw lines to join each electrode with the correct product formed.

Use Fig. 5.1 to help you.

Atoms contain a nucleus surrounded by electrons.

The nucleus contains protons and neutrons.

Which statements about the nucleus are true and which are false ?

Tick (✓) one box in each row.

Magnesium atoms react with oxygen atoms to form magnesium oxide.

Magnesium oxide contains magnesium ions and oxygen ions.

Fig. 6.1 shows the number and arrangement of electrons in a magnesium atom and an oxygen atom.

Some metals react with bromine to form metal bromides.

The table shows information about some metal bromides.

Complete the table by filling in the blank spaces.

Metal bromides have high melting points.

Which statements about metal bromides are true and which are false ?

Tick (✓) one box in each row.

Hydrogen peroxide (H₂O₂) is made in the body.

An enzyme breaks down hydrogen peroxide into oxygen gas and water before it can damage cells in the body.

Ali adds this enzyme to some hydrogen peroxide.

He measures the volume of oxygen gas made.

The hydrogen peroxide does not break down to make oxygen gas until Ali adds the enzyme.

Which statement explains why?

Tick (✓) one box.

Ali then adds the enzyme to different concentrations of hydrogen peroxide.

He finds that the reaction is faster when the concentration of hydrogen peroxide solution is higher.

Explain why the reaction is faster.

Use ideas from the particle model in your answer.

Ali does more experiments.

He makes some solutions of hydrogen peroxide with different pH values.

Describe one method of measuring the pH of each solution.

Ali adds the enzyme to these solutions of hydrogen peroxide with different pH values.

He finds that the rate of reaction increases when pH values increase from 1 to 6.

He finds that the rate of reaction decreases when pH values increase from 6 to 7.

Use ideas about enzymes to explain these results.

James uses charcoal as a fuel for his barbecue.

Charcoal is a form of carbon. When charcoal burns in plenty of oxygen it forms carbon dioxide.

How could you test that the gas formed is carbon dioxide?

Explain why burning charcoal without enough oxygen can cause a health hazard.

Fig. 9.1 shows the reaction profile for charcoal burning in air.

Draw lines to connect each letter with its correct label.

James uses a firelighter.

The firelighter burns with a hot flame which makes the charcoal start to burn.

Which two statements explain how the firelighter makes the charcoal start to burn?

Tick (✓) two boxes.

Alkanes are a family of hydrocarbons in crude oil. They all have the same general formula, C_nH_2n+2.

Table 10.1 shows some information about alkanes.

Complete the blank spaces in Table 10.1 to show the missing formulae.

Which statements about a structural formula are true and which are false ?

Tick (✓) one box in each row.

Predict the boiling point of hexane.

Use the data in Table 10.1 to help you.

What is the state of pentane at 25 °C?

Explain your answer.

State:........

Explanation:........

Explain the trend in boiling points in Table 10.1.

Use ideas about energy and intermolecular forces in your answer.

Carbon nanotubes were discovered in 1991.

Materials made from nanotubes can be used instead of steel because nanotubes are very strong. They are a few nanometres wide and up to 1 cm long.

The structure of a nanotube is shown below.

Nanotubes are nanoparticles.

Which statement explains why nanotubes are nanoparticles?

Tick (✓) one box.

Which two statements explain why nanotubes are very strong?

Tick (✓) two boxes.

Nanotubes are a similar shape to a human hair but they are much smaller.

A human hair has a diameter of 0.001 mm. A nanotube has a diameter of 2 nm and a length of 5 mm.

A scale model of a nanotube has the same diameter as a human hair.

What is the length of the scale model in mm?

1 nm = 1 × 10^–6 mm

Short nanotubes can also be used to carry medicines into the body.

The medicine is put inside the tube and the tube is injected into the body.

Give one benefit and one risk of using nanotubes to carry medicines into the body.

Benefit

Risk