Helium, neon, argon, krypton, xenon and radon are noble gases in Group VIII.
- (a)Name the noble gas which has the greatest volume composition in air.[1]
- (b)State one use for helium.[1]
- (c)Radon is very unreactive. Use the electronic structure of radon to explain why.[1]
- (d)Two isotopes of radon are shown. 220Rn 86 222Rn 86
- (d)(i)Give one similarity in the atomic structure of these two isotopes.[1]
- (d)(ii)Give one difference in the atomic structure of these two isotopes.[1]
- (e)Xenon forms a compound that contains only xenon, oxygen and fluorine. The compound contains 22.1% oxygen by mass and 17.5% fluorine by mass. Calculate the empirical formula of this compound.[3]
- (f)A sample of neon has a volume of 21 dm³ at room temperature and pressure.
- (f)(i)The temperature of the sample is increased. The pressure remains constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample.[1]
- (f)(ii)The pressure of the sample is increased. The temperature remains constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample.[1]
- (f)(iii)Calculate the mass of neon in the 21 dm³ sample. Give your answer to two significant figures.[2]
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Mark scheme
Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.
- 2(a) argon
- 2(b) (air) balloons / undersea breathing apparatus
- 2(c) outer shell has 8 electrons
- 2(d)(i) 86 protons/86 electrons / same electronic structure
- 2(d)(ii) radon-222 has two more neutrons / radon-220 has two fewer neutrons / radon-220 has 134 neutrons and radon-222 has 136 neutrons
- 2(e) percentage of xenon = 60.4 (1)
- 2(e) mole ratio Xe : O : F is 60.4/130 : 22.1/16 : 17.5/19
- 2(e) OR 0.46 : 1.38 : 0.92 (1)
- 2(e) empirical formula XeO3F2 (1)
- 2(f)(i) volume increases
- 2(f)(i) AND particles move faster / particles spread out more / particles move further apart
- 2(f)(ii) volume decreases
- 2(f)(ii) AND particles move closer together / distance between particles decreases
- 2(f)(iii) moles = 21/24 OR 0.875 (1)
- 2(f)(iii) mass = 18 (g) (1)
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