State the symbol of the element that is a gaseous fuel at room temperature.
State the symbol of the element used to kill bacteria in water.
State the symbol of the element that produces a stable ion of the form $X^{3+}$.
State the symbol of the element that is a grey-black non-metallic solid at room temperature.
State the symbol of the element whose ion forms a white precipitate when aqueous sodium hydroxide is added, and whose precipitate dissolves in excess aqueous sodium hydroxide.
Identify one correct statement about isotopes. Tick one box. They are molecules that have equal numbers of neutrons but different numbers of protons. They are atoms that have the same number of protons but different numbers of neutrons. They are molecules that have the same number of protons but different numbers of electrons. They are atoms that have the same number of neutrons but different numbers of protons.
Deduce the number of protons and the number of neutrons in this isotope. proton count neutron count
Complete the electronic structure for a sulfur atom.