Question 23M.2.HL.TZ1.5

Weak nuclear: 2 ticks ✓
Strong nuclear: quarks only ✓

«𝜇» = 2.0141 + 3.0160 − (4.0026 + 1.008665) «= 0.0188 u»

OR

In MeV: 1876.13415 + 2809.404 − (3728.4219 + 939.5714475) ✓

= 0.0188 × 931.5 OR = 17.512 «MeV» ✓

Must see either clear substitutions or answer to at least 3 s.f. for MP2.

ALTERNATIVE 1

0.40 kg of deuterium is «$\frac{400}{2}$ × 6.02 × 10²³» = 1.2 × 10²⁶ nuclei
« 0.60 kg of tritium is the same number » ✓

So specific energy «$\frac{1.2\times {10}^{26}\times 17.51\times {10}^6\times 1.6\times {10}^{-19}}{0.4+0.6}$» = 3.4 × 10¹⁴ «J kg⁻¹»

ALTERNATIVE 2

«17.51 × 10⁶ × 1.6 × 10⁻¹⁹ =» 2.8 × 10⁻¹² «J»

AND

«(2.0141 + 3.0160) × 1.66 × 10⁻²⁷ =» 8.35 × 10⁻²⁷ ✓

«$\frac{2.8\times {10}^{-12}}{8.35\times {10}^{-37}}$» = 3.4 × 10¹⁴ «J kg⁻¹»

Allow ∼2.1 × 10²⁷ MeV kg⁻¹ for MP2.

Allow ECF from MP1 for both ALTs.

Requires high temp/pressure ✓
Must overcome Coulomb/intermolecular repulsion ✓
Difficult to contain / control «at high temp/pressure» ✓
Difficult to produce excess energy/often energy input greater than output / OWTTE ✓
Difficult to capture energy from fusion reactions ✓
Difficult to maintain/sustain a constant reaction rate ✓

Plentiful fuel supplies OR larger specific energy OR larger energy density OR little or no «major radioactive» waste products ✓

Allow descriptions such as “more energy per unit mass” or “more energy per unit volume”

3 ✓

Do not accept ${}_{\mathit{2}}{}^{\mathit{3}}He$ by itself.

Proton shown ✓

W- shown ✓

Produces electron/e⁻ / 𝛽⁻ and antineutrino / $\overline{v}$ with proper arrow directions. ✓

Allow solid, dashed, or wavy line for W-particle.

Must see bar on antineutrino if symbol used.

$\lambda$ = «$\frac{\ln 2}{12.3}$»0.056«y⁻¹»  OR  $0.5^{\frac{1}{12.3}}$  OR  $e^{-1\times \frac{\ln 2}{12.3}}$

0.945 OR 94.5% ✓

Allow ECF from MP1