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GCSE Chemistry (OCR)

Atomic structure, bonding, quantitative, rates, organic, analysis. OCR board.

Pass mark 24/40 60 minutes OCR How many can I get wrong?
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Q1. Which particle has a relative charge of −1 and a relative mass of approximately 0?
  • A.  Electron
  • B.  Proton
  • C.  Neutron
  • D.  Nucleus
Show answer & explanation
✓ Answer: A. Electron
Electrons carry a relative charge of −1 but their mass (1/1836 of a proton) is treated as negligible on the relative mass scale. Protons and neutrons both have a relative mass of 1, so they cannot be the answer.
Q2. A student says an ionic bond is formed by 'sharing' electrons between a metal and a non-metal. What is wrong with this statement?
  • A.  Ionic bonding involves the transfer of electrons, not sharing
  • B.  Metals never lose electrons to non-metals
  • C.  Ionic bonds only form between two non-metals
  • D.  Sharing only happens in metallic bonding
Show answer & explanation
✓ Answer: A. Ionic bonding involves the transfer of electrons, not sharing
In ionic bonding, electrons are transferred from a metal atom to a non-metal atom, creating oppositely charged ions that then attract each other. Sharing of electron pairs is the mechanism of covalent bonding, which occurs between non-metal atoms.
Q3. In the reaction N2 + 3H2 -> 2NH3, if 1 mol of N2 is mixed with 2 mol of H2, which reactant is limiting?
  • A.  H2, because 3 mol would be needed to fully react with all the N2
  • B.  N2, because it has the smaller starting number of moles
  • C.  Neither, because both reactants are used up at exactly the same time
  • D.  H2, because it has a lower relative formula mass than N2
Show answer & explanation
✓ Answer: A. H2, because 3 mol would be needed to fully react with all the N2
The ratio required is 1 mol N2 to 3 mol H2, but only 2 mol H2 is available, so H2 runs out first and limits the reaction. Simply having fewer starting moles (as N2 does) does not automatically make a reactant limiting; the stoichiometric ratio must be checked.
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Atomic structure & the periodic table · 34
Bonding, structure & properties · 39
Quantitative chemistry · 37
Chemical changes & energy · 35
Rates, equilibrium & organic · 38
Chemical analysis & the atmosphere · 35
GCSE Chemistry (OCR) — common questions
Frequently asked
How many questions are in the GCSE Chemistry (OCR)?
The exam has 40 questions. Every Revision Robin mock uses the same 40-question format so your practice matches the real thing.
What is the pass mark for the GCSE Chemistry (OCR)?
You need 24 out of 40 correct to pass, which is about 60%. Our mocks mark you against this exact threshold.
How long do you get?
The test is timed at 60 minutes. Our full mock runs on the same clock so you can practise your pacing.
Are these the real exam questions?
No. Our questions are original and written to match the current syllabus, so they give realistic practice without copying the official paper. Every answer comes with a plain-English explanation. Always confirm current rules and content with OCR.