Decide which element probably has a density most and least similar to the density of strontium.
The element that probably has a density most similar to strontium is calcium. Both strontium and calcium are in the same group (Group 2) of the periodic table, and elements in the same group tend to have similar properties.
The element that probably has a density least similar to strontium is hydrogen. Hydrogen is a gas at room temperature and pressure, and has a much lower density compared to solid elements like strontium.