Question
(a) Explain, in terms of molecules, how a gas causes a pressure on the walls of its container.
…………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………. [4]
(b) Complete the following two sentences.
(i) At constant temperature, the pressure of a gas increases as its volume
………………………………………. .
(ii) At constant volume, the pressure of a gas increases as its temperature
………………………………………. . [Total: 6]
Answer/Explanation
Ans: (a) they/molecules/particles/atoms moving/vibrating/have KE they/molecules/particles/atoms collide (condone with each other)
they/molecules/particles/atoms collide with walls extra relevant information e.g. exert force, change of momentum, bounce back/off,
lots over an area, random/Brownian motion
(b) (i) decreases
(ii) increases
Question
(a) A metal ruler with a rectangular cross-section is heated in an oven.
State two things that happen to the atoms of the metal.
1. ……………………………………………………………………………………………………………….
2. ……………………………………………………………………………………………………………….[2]
State what happens to
1. the length of the ruler, ………………………………………………………………………………
2. the width of the ruler, ………………………………………………………………………………..
3. the thickness of the ruler. ………………………………………………………………………….. [2]
(b) The nut in Fig. 5.1 has become jammed on the bolt, so that it will not rotate.
Explain why heating the nut with a very hot flame is likely to free the jammed nut.
…………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………….. [2] [Total: 6]
Answer/Explanation
Ans: (a) (i) move/vibrate/oscillate faster OR increase/gain KE move (further) apart OR (they) separate
(ii) any 1 increases/enlarges/gets bigger/expands o.w.t.t.e. all three increase
(b) nut/hole expands/enlarges ignore particles expand/enlarge bolt doesn’t expand (as much)