Paper 1 Atomic Structure Answers

Q	Answer	Reason
1	B	Scattering showed nuclear atom.
2	B	Most volume is empty space.
3	A	Rare strong deflections need dense positive nucleus.
4	A	Downward transition emits photon.
5	A	Absorption requires exact energy gap.
6	B	Zero level is free electron at infinity.
7	B	Standard atomic convention.
8	B	Bound states have negative energy.
9	A	Photon energy equals level difference.
10	A	$\lambda =hc/\Delta E$.
11	B	Discrete wavelengths imply discrete energy differences.
12	C	The nucleus contains protons and neutrons.
13	A	Same element, different neutron count.
14	B	Specific charge is charge per unit mass.
15	A	Coulomb repulsion.
16	A	Photons removed from original beam direction.
17	D	The electron energy increases by $3.0\mathrm{eV}$, so this energy must be absorbed.
18	A	Energy decreases by 2.5 eV.
19	A	Each allowed pair can produce a line if transition occurs.
20	B	The classical Rutherford model did not account for stable quantised levels and discrete spectra.