Oxygen, sulfur, selenium, tellurium and polonium are in Group VI.

1. (a)State the percentage composition by volume of oxygen in dry air.[1]
2. (b)State one large-scale use for oxygen.[1]
3. (c)(i)Explain why both isotopes have the same chemical properties.[1]
4. (c)(ii)Give one difference in the atomic structure of these two isotopes.[1]
5. (d)Selenium forms a compound that contains only selenium, oxygen and chlorine. The compound contains 9.6% oxygen by mass and 42.8% chlorine by mass. Calculate the empirical formula of this compound. empirical formula[3]
6. (e)(i)The temperature of the sample is decreased. The pressure remains constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample.[1]
7. (e)(ii)The pressure of the sample is decreased. The temperature remains constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample.[1]
8. (e)(iii)Calculate the mass of oxygen in the 11.5dm³ sample at room temperature and pressure. Give your answer to two significant figures. mass ... g[2]

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