State the volume percentage of oxygen in dry air.
State one major large-scale use of oxygen.
Two isotopes of polonium are shown: $^{209}_{84}\text{Po}$ and $^{210}_{84}\text{Po}$. Explain why these isotopes have the same chemical properties.
Give one way in which the atomic structures of these two isotopes differ.
A selenium compound contains only selenium, oxygen and chlorine. It has 9.6% oxygen by mass and 42.8% chlorine by mass. Calculate the empirical formula of the compound.
A sample of oxygen has a volume of 11.5 dm$^3$ at room temperature and pressure. The temperature of the sample is lowered while the pressure stays constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample.
The pressure of the sample is decreased while the temperature remains constant. Describe and explain, using kinetic particle theory, what happens to the volume of the sample.
Calculate the mass of oxygen present in the 11.5 dm$^3$ sample at room temperature and pressure. Give your answer to two significant figures.