GCSEScienceOCRCombined Science A (Gateway)ChemistryExam QuestionsPractical SkillsPractical Skills

Practical Skills (OCR GCSE Combined Science A (Gateway): Chemistry): Exam Questions

Exam code: J250

37 mins15 questions

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Easy
Medium
Hard
1
1 mark

Which statement correctly describes a test for oxygen gas?

  • A lighted splint makes a squeaky pop

  • Limewater turns milky

  • A glowing splint re-lights

  • Damp litmus paper is bleached

Choose your answer

2
1 mark

What is the reading on the following thermometer?

7-1-q10-ocr-gcse-chemistry-mcq

  • 28.3 oC

  • 28.6 oC

  • 29.2 oC

  • 28.5 oC

Choose your answer

3
1 mark

What is the correct expression for calculating the Rf value in chromatography?

  • Rf = distance the solute travelsdistance the solvent travels

  • Rf = distance the solvent travelsdistance the solute travels

  • Rf = distance the mobile phase travelsdistance the stationary phase travels

  • Rf = distance the stationary phase travelsdistance the mobile phase travels

Choose your answer

1
1 mark

A laboratory experiment to separate crude oil is shown below.

q9-2-2-lab-experiment-for-separating-crude-oil

Which row is correct? 

 

The process taking place at X

The process taking place at Y

A

decomposition

condensation

B

evaporation

reduction

C

distillation

reduction

D

evaporation

condensation

    Choose your answer

    2
    1 mark

    Below are five steps in the preparation of a soluble salt. The sentences are not in the correct order.

    1. Heat to evaporate most of the water

    2. Add solid copper(II) oxide until no more dissolves

    3. Measure out 25 cm3 of dilute sulfuric acid

    4. Leave in a warm place to cool and crystallise

    5. Filter to remove the excess solid

    What is the correct order of the sentences?

    • 5,1,4,3,2

    • 2,5,3,1,4

    • 3,2,5,1,4

    • 5,1,3,2,4

    Choose your answer

    3
    1 mark

    A student wants to investigate the effect of surface area on the rate of reaction between marble chips and dilute acid.

    What pieces of apparatus would be essential to this investigation?

    • Burette, beaker, pipette

    • Ruler, thermometer, test tube

    • Balance, measuring cylinder, stopwatch

    • Filter funnel, evaporating basin, Bunsen burner

    Choose your answer

    4
    1 mark

    A student sets up the following laboratory apparatus.

    7-1-q9-ocr-gcse-chemistry-mcq-

    Which reaction could the student be investigating?

    • Cracking liquid paraffin

    • The effect of concentration in the reaction between marble chips and dilute hydrochloric acid

    • The neutralisation of dilute hydrochloric acid by solid calcium hydroxide

    • The displacement reaction between chlorine solution and aqueous potassium bromide

    Choose your answer

    5
    1 mark

    A student investigates the reaction between sodium thiosulfate and hydrochloric acid. Look at the diagram below. It shows the apparatus he uses.

    q4-paper-2-specimen-2016-ocr-gcse-chem

    • After a time he cannot see the cross because the liquid in the conical flask goes cloudy. The student measures the time taken until the cross cannot be seen.

    • He does the experiment four times. For each experiment he uses a different concentration of sodium thiosulfate solution.

    Which of the following must not be changed to do a fair test?

    • Concentration of sodium thiosulfate

    • Stop-clock or timer

    • Total volume of the reaction mixture

    • Volume of sodium thiosulfate added

    Choose your answer

    6
    1 mark

    A student wants to test the purity of a liquid by testing its boiling point.

    The actual boiling point of the pure liquid is 85 °C.

    Which equation represents the percentage (%) difference between the student’s value and the actual value?

    • % difference = 100 × (student’s value in °C) – 85 °C85 °C

    • % difference = 100 × 85 °C – (student’s value in °C)85 °C

    • % difference = (student’s value in ºC) – 85 °C85 °C

    • % difference = 85 °C – (student’s value in °C)85 °C

    Choose your answer

    1
    1 mark

    On a chromatogram, a substance has an Rf value of 0.68.  

    If the solvent front travels 9 cm from the baseline, at what distance from the baseline will the spot be found. 

    • 0.1

    • 5.1

    • 6.0

    • 6.1

    Choose your answer

    2
    1 mark

    Paper chromatography was used to determine if a banned preservative, X, is present in four samples obtained from four different packaged foods labelled A, B, C and D.

    The results of the analysis of the foodstuffs are shown in the diagram below.

    q2-easy-mcq-12-2-separation-purification-cie-igcse-chemistry

    Which foodstuff contains X?

      Choose your answer