Describe how the plum pudding model of the atom was replaced by the nuclear model.
24 marks
Describe how sodium and chlorine atoms form an ionic compound. You may use dot-and-cross diagrams.
32 marks
Calculate the relative formula mass (Mr) of CaCO₃. (Relative atomic masses: Ca = 40, C = 12, O = 16)
46 marks
Describe how to prepare a pure, dry sample of copper(II) sulfate crystals from copper(II) oxide and dilute sulfuric acid.
54 marks
Predict the products at each electrode in the electrolysis of copper(II) chloride solution and write the half equation at the cathode.
63 marks
Explain the difference between exothermic and endothermic reactions, with an example of each.
73 marks
An atom of potassium has mass number 39 and atomic number 19. Give the numbers of protons, neutrons and electrons.
83 marks
Explain why sodium chloride has a high melting point and conducts electricity when molten but not when solid.
92 marks
Calculate the relative formula mass (Mr) of Mg(OH)₂. (Relative atomic masses: Mg = 24, O = 16, H = 1)
103 marks
Explain the difference between a strong acid and a weak acid.
114 marks
Explain the products of electrolysis of sodium chloride solution (brine).
124 marks
Use the bond energies (kJ/mol) H–H 436, Cl–Cl 243, H–Cl 432 to calculate the energy change for H₂ + Cl₂ → 2HCl.
132 marks
An element has two isotopes: mass 35 (75%) and mass 37 (25%). Calculate its relative atomic mass.
143 marks
Explain why methane has a low boiling point.
152 marks
Calculate the relative formula mass (Mr) of H₂SO₄. (Relative atomic masses: H = 1, S = 32, O = 16)
162 marks
The pH of an acid changes from 2 to 4. By what factor has the hydrogen ion concentration changed?
173 marks
Explain why ionic compounds must be molten or dissolved to be electrolysed.
184 marks
Use the bond energies (kJ/mol) H–H 436, O=O 498, O–H 464 to calculate the energy change for 2H₂ + O₂ → 2H₂O.
192 marks
An element has two isotopes: mass 63 (69%) and mass 65 (31%). Calculate its relative atomic mass.
201 mark
Which substance has a giant covalent structure?
Finished?
Answer every question to finish (20 left), or finish when the time’s up.
Score 0 / 60 · 0 of 20 marked
This paper is written by Plasmo in the style of the OCR GCSE Combined Science exam. It is not a past paper and is not produced or endorsed by the exam board.