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GCSE Chemistry (Edexcel)

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

Pass mark 24/40 60 minutes Edexcel How many can I get wrong?
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Q1. An atom of sodium has atomic number 11 and mass number 23. How many neutrons does it contain?
  • A.  11
  • B.  12
  • C.  23
  • D.  34
Show answer & explanation
✓ Answer: B. 12
Number of neutrons = mass number - atomic number = 23 - 11 = 12. Choosing 11 confuses neutrons with protons, and 23 confuses neutrons with the mass number itself.
Q2. Why do ionic compounds such as sodium chloride have high melting points?
  • A.  The molecules are very large and heavy
  • B.  There are many weak intermolecular forces to overcome
  • C.  There are strong electrostatic forces between oppositely charged ions throughout the giant lattice, which need a lot of energy to break
  • D.  The delocalised electrons hold the ions together very tightly
Show answer & explanation
✓ Answer: C. There are strong electrostatic forces between oppositely charged ions throughout the giant lattice, which need a lot of energy to break
Ionic compounds form giant lattices with strong electrostatic attractions extending in all directions between oppositely charged ions. A large amount of thermal energy is needed to overcome these many strong forces, giving high melting and boiling points. Ionic compounds do not consist of molecules.
Q3. What is the empirical formula of a compound containing 40% carbon, 6.7% hydrogen and 53.3% oxygen by mass? (Ar: C=12, H=1, O=16)
  • A.  CH2O
  • B.  C2H4O2
  • C.  CHO
  • D.  C2H6O
Show answer & explanation
✓ Answer: A. CH2O
Divide by Ar: C = 40/12 = 3.33, H = 6.7/1 = 6.7, O = 53.3/16 = 3.33. Dividing all by the smallest (3.33) gives ratio C:H:O = 1:2:1, so the empirical formula is CH2O.
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Atomic structure & the periodic table · 34
Bonding, structure & properties · 35
Quantitative chemistry · 66
Chemical changes & energy · 35
Rates, equilibrium & organic · 38
Chemical analysis & the atmosphere · 36
GCSE Chemistry (Edexcel) — common questions
Frequently asked
How many questions are in the GCSE Chemistry (Edexcel)?
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 (Edexcel)?
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 Edexcel.