4   6 In a particular radioactive decay, there is a mass decrease equivalent to 0.05 u. Which of the following expressions gives the energy released in MeV? A 0 05 1 66 10 3 10 1 6 10 27 8 2 19 . . . B 0 05 1 67 10 3 10 1 6 10 27 8 2 19 . . . C 0 05 1 66 10 3 10 1 6 10 27 8 2 13 . . . D 0 05 1 67 10 3 10 1 6 10 27 8 2 13 . . . (Total for Question 6 = 1 mark) 7 Air is trapped in a glass tube. When the air is forced into a smaller volume at a constant temperature, the pressure increases. Which of the following statements about air molecules is a reason why the pressure the trapped air exerts on the tube increases? A The molecules have a greater mean kinetic energy. B The molecules make more frequent collisions with each other. C The molecules make more frequent collisions with the walls of the tube. D The molecules experience a greater change in momentum when they collide with the tube. (Total for Question 7 = 1 mark) Turn over 5   8 Total internal reflection occurs when light is incident on the boundary between medium 1 and medium 2, as shown. medium 2 medium 1 θ θ The refractive index of medium 1 is n1 and the refractive index of medium 2 is n2. The critical angle for the boundary is C. Which row of the table is correct? A B C D θ < C n1 > n2 θ < C n2 > n1 θ > C n1< n2 θ > C n2 < n1 (Total for Question 8 = 1 mark)