Answer Happy

Question 16 (based on material in Units 24 and 25) Sodium (Na) has atomic number 11. An isotope called sodium-22 decays into an isotope of neon (Ne) by 3+ decay. The half-life of this decay reaction is 2.60 years. (a) How much time does it take for the number of sodium-22 atoms in a sample to fall to 5.00% of those initially present? (b) (i) Give the numbers of protons and neutrons for each of the sodium and neon nuclei in this decay reaction. (ii) Considering your answer to part (i), give two brief reasons why you would expect the sodium nucleus in this decay reaction to be less stable than the neon nucleus. (c) (i) Write down an expression for this specific decay reaction. Define the symbols in your expression. (ii) Show that charge, baryon number and lepton number are each conserved in this decay reaction. (iii) Explain why the exchange boson in this decay reaction must be W+. (iv) For each of the final particles produced by this decay reaction, state whether it feels the weak force. [4] [2] [2] [3] [5] [2] [2]