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(1) . (1) (0) (b) 1 (1) (c) 1 1/1 (11) 1/1 (11) De (1) (11) " za (1) R- (d) 1 3/1 (0) (11) (1) (1) 1/1 (1) 1/1 (1) (1) (11) In circuit (i) above, the current I was measured as a function of the resistance R, for a single cell of emf e and internal resistance r. In circuit (ii) above, the current I was measured as a function of the resistance R. for two identical cells, each of emf € and internal resistance r, connected in parallel. Which of the graphs above correctly shows the dependence of 1/1 vs R for the two cases? (b) (a) le 1) 3

Activity 100 200 400 500 300 Time (s) —+ The graph above shows thč activity of a radon source as a function of time. Which one of the following is nearest to the half - life, t1/2? 250 s. 100 s. 80 s. O 50 s. 120 s