State which positive ion has the smallest mass in 1000 cm$^3$ of fruit juice.
State the formulae of the ions in calcium sulfate.
Calculate the mass of magnesium ions present in 250 cm$^3$ of fruit juice.
Describe a test for calcium ions. Include both the test and the observations.
Ammonium ions, NH$_4^+$, occur in most fertilisers. Ammonium ions contain nitrogen. Name two further elements found in most fertilisers.
A student heated a mixture of ammonium chloride and sodium hydroxide in a test-tube. Pungent ammonia gas is released. Describe one further observation that can be made.
Ammonia reacts with chlorine. Complete the equation for this reaction: $\ldots$NH$_3$ + $\ldots$Cl$_2$ $\rightarrow$ N$_2$ + 6HCl.
A small beaker of aqueous ammonia is set at the front of a classroom. At first, the students at the back of the class cannot smell the ammonia gas. After a short time, the students at the back of the class smell the ammonia. Explain these observations using the kinetic particle model.