GCSEChemistry: Combined ScienceOCR GatewayExam Questions7. Practical Skills7.1 Practical Skills

Practical Skills (OCR Gateway GCSE Chemistry: Combined Science)

Exam Questions

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7.1 Practical Skills

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7.1 Practical Skills

11 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

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    21 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

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    31 mark

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

    • Error converting from MathML to accessible text.

    • size 14px R subscript size 14px f size 14px space size 14px equals size 14px space fraction numerator size 14px distance size 14px space size 14px the size 14px space size 14px solvent size 14px space size 14px travels over denominator size 14px distance size 14px space size 14px the size 14px space size 14px solute size 14px space size 14px travels end fraction

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    41 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

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    51 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

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    61 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

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    71 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

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    81 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 × fraction numerator left parenthesis student ’ straight s space value space in space degree straight C right parenthesis space – space 85 space degree straight C over denominator 85 space degree straight C end fraction

    • % difference = 100 × fraction numerator 85 space degree straight C space – space left parenthesis student ’ straight s space value space in space degree straight C right parenthesis over denominator 85 space degree straight C end fraction

    • % difference = fraction numerator left parenthesis student ’ straight s space value space in space º straight C right parenthesis space – space 85 space degree straight C over denominator 85 space degree straight C end fraction

    • % difference = fraction numerator 85 space degree straight C space – space left parenthesis student ’ straight s space value space in space degree straight C right parenthesis over denominator 85 space degree straight C end fraction

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