Exam-style Questions: Matter and Antimatter

1. The atomic bomb dropped on Hiroshima had an explosive energy of 8.4 x 1013J. How many kilograms of mass must have been converted into energy in this explosion?

(Marks available: 1)

Answer outline and marking scheme for question: 1

9.3 x 10-4kg

(Marks available: 1)

2. Lawrence, the inventor of the cyclotron, produced an early model with a diameter of 25cm. It could accelerate protons up to an energy of 1 MeV.

Calculate:

a) The speed of the protons produced.

b) The flux density of the magnetic field that would be required

c) The frequency at which the p.d. across the Ds must change

Mass of proton = 1.7 x 10-27Kg

Charge of proton = 1.6 x 10-27C

(Marks available: 3)

Answer outline and marking scheme for question: 2

a) 1.4 x 107ms-1

b) 1.2 T

c) 17MHz

(Marks available: 3)

3. a) The following series of reactions occur inside the Sun.

Write nuclear equations to represent these reactions.

i) Two hydrogen-1 nuclei fuse to produce hydrogen-2 (deuterium) nucleus and a positron.

(1 Mark)

ii) The hydrogen-2 nucleus fuses with another hydrogen-1 nucleus to produce helium-3.

(1 Mark)

iii) Two helium-3 nuclei then fuse to give helium-4 two hyrdrogen-1 nuclei.

(1 Mark)

b) Use your answers to (i), (ii) and (iii) to deduce an equation which summarises the fusion of hydrogen-1 nuclei to forma helium-4 nucleus.

(2 Marks)

(Marks available: 5)

Answer outline and marking scheme for question: 3

a) i) 11H + 11H → 21H + 01β (+v)

(1 Mark)

ii) 21H + 11H → 32He

(1 Mark)

iii) 32He + 32He → 42He + 211H

(1 Mark)

b) 32He + 32He→ 42He + 211H

221H + 211H → 232He

211H + 211H → 221H + 201β (+2v) (allow β+ or 01e)