A-LevelPhysicsNuclear physics9702/23 · May/June 2021 · Q69 Marks

State the quark composition of:

(a)State the quark composition of:
(a)(i)a proton[1]
(a)(ii)a neutron[1]
(a)(iii)an alpha-particle.[2]
(b)In the alpha-particle scattering experiment, alpha-particles were directed at a thin gold foil. State what may be inferred from:
(b)(i)the observation that most alpha-particles pass through the foil[1]
(b)(ii)the observation that some alpha-particles are scattered through angles greater than 90°.[2]
(c)A proton and an alpha-particle are moving in the same uniform electric field. Determine the ratio acceleration of proton due to the electric field ---------------------------------------------------------------------------------- acceleration of alpha-particle due to the electric field ratio = ............................................................[2]

Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

[B1] up up down
[B1] up down down
[C1] (alpha-particle is) 2 protons and 2 neutrons
[A1] 6 up, 6 down
[B1] most of an atom is empty space OR the nucleus (volume) is (very) small compared with the atom
[B1] the nucleus is charged
[B1] the majority of the mass of atom is in the nucleus
[C1] F = Eq and a = F/m (implies a = Eq/m)
[A1] ratio = (e/m_p) / (2e/4m_p) = 2

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