A-LevelPhysicsNuclear physics9702/22 · Feb/Mar 2025 · Q77 Marks
An isolated stationary nucleus Q decays into nucleus R and an α-particle. The α-particle has speed 1.5 x 10⁷ms⁻¹.
- (a)Complete the equation for this decay. ⁸⁸Q → ²²²R + α[1]
- (b)By considering momentum, calculate the speed of nucleus R after the decay. speed = ................................................................ms⁻¹ [3][3]
- (c)State three quantities that are conserved during the decay. 1 .................................................................................................................................................................... 2 .................................................................................................................................................................... 3 .................................................................................................................................................................... [3][3]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2025). The mark or mark type is shown in brackets.
- B1 nucleon number of Q = 226 and proton number of R = 86
- C1 4(u) x 1.5 x 107 or 222(u) × V
- C1 v = 4(u) x 1.5 × 107 / 222(u)
- A1 = 2.7 x 105 m s-1
- B3 Any three from:
- • momentum
- • charge
- • nucleon number
- • neutron number
- • proton number
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