A-Level Physics: Nuclear and Astrophysics Practice

An atom of potassium-40 has 19 protons. How many neutrons does it contain?

The binding energy per nucleon of iron-56 is approximately 8.79 MeV. What is the total binding energy of an iron-56 nucleus?

On a graph of neutron number N against proton number Z, stable nuclei that lie above the stability curve (excess neutrons) are likely to undergo which type of radioactive decay?

A radioactive isotope has a half-life of 5.0 days. Starting with 160 g of the isotope, how much remains after 20 days?

A radioactive sample contains 4.0 x 10^15 nuclei with a decay constant of 1.2 x 10^-6 s^-1. What is its activity?

A piece of ancient wood has 25% of the carbon-14 activity of a living sample. The half-life of carbon-14 is 5730 years. How old is the wood?

In a nuclear fission reactor, which component absorbs neutrons to control the rate of the chain reaction?

In a typical fission of U-235, approximately 200 MeV of energy is released per nucleus. Calculate the total energy released when 1.0 g of U-235 undergoes complete fission. (N_A = 6.02 x 10^23 mol^-1, 1 eV = 1.6 x 10^-19 J)

The proton-proton chain is the dominant fusion process in main sequence stars like the Sun. What minimum core temperature is required for fusion to begin, and what physical barrier must be overcome?

A pi-plus meson (pi+) has a charge of +1e. What is its quark composition?

A free neutron undergoes beta-minus decay: n -> p + e- + anti-nu_e. Which quantities are conserved in this process?

A positron (e+) and an electron (e-) annihilate producing two gamma ray photons. Why must exactly two photons be produced rather than one?

On the Hertzsprung-Russell diagram, where are approximately 90% of stars located?

What primarily determines whether a star ends its life as a white dwarf, neutron star or black hole?

The Chandrasekhar limit is approximately 1.4 solar masses. What is its physical significance?

What does cosmological redshift of light from distant galaxies indicate?

Given Hubble's constant H_0 = 68 km/s/Mpc, estimate the age of the universe using t = 1/H_0. (1 Mpc = 3.086 x 10^19 km, 1 year = 3.156 x 10^7 s)

The cosmic microwave background (CMB) radiation has a blackbody spectrum with a peak wavelength of 1.06 mm. Using Wien’s displacement law (lambda_max * T = 2.90 x 10^-3 m K), what is the temperature of the CMB and what does it represent?