A student says: "Evaporating a molecular liquid makes smaller molecules because the bonds break."
Explain what happens during evaporation and evaluate the student claim.
[6 marks]OCR Gateway GCSE Chemistry June 2018 Paper 3
5 questions on this paper's topics
32:001 of 5
A student adds an alkali gradually to an acid. The measured pH values after successive additions are 2, 4, 6, 7, 9 and 11.
.1
Describe the change and identify the neutral reading.
[2 marks].2
Explain neutralisation in terms of the reacting ions.
[2 marks]An element has only isotopes X-50 and X-54. Its measured relative atomic mass is 51.2.
.1
Calculate the percentage abundance of X-54.
[3 marks].2
Evaluate a claim that the two isotopes are equally abundant.
[2 marks]A student claims that discovering the electron was enough evidence for the modern nuclear model of the atom.
Evaluate the claim using the development of atomic models.
[6 marks]Copper oxide is reduced by hydrogen: . A process must produce 12.8 g copper. : Cu = 64, O = 16, H = 1.
.1
Calculate the minimum mass of copper oxide needed if conversion is complete.
[4 marks].2
Calculate the mass of hydrogen that reacts with this copper oxide.
[2 marks]