Deep-sea hydrothermal vents, or 'black smokers', are extreme environments on the ocean floor. The water temperature around these vents can reach about 380 ∘C380\ ^\circ\text{C}380 ∘C. Additionally, the fluid venting into the ocean is highly acidic, containing dissolved hydrochloric acid (HCl\text{HCl}HCl). A research organization is designing a robotic probe to descend to these vents and sample the fluids. To make deployment easier, the weight of the probe should be kept as low as possible. The probe must also survive the high temperatures and acidic environment. The table below lists some properties of metals that could be used to build the probe.
MetalMelting point (∘C)Relative densityReaction with hydrochloric acidAluminium6602.7reacts rapidlyCopper10838.9no reactionNickel14558.9reacts slowlyTin2327.3reacts slowlyTitanium16684.5no reactionZinc4207.1reacts vigorously \begin{array}{|l|c|c|l|} \hline \textbf{Metal} & \textbf{Melting point } (^\circ\text{C}) & \textbf{Relative density} & \textbf{Reaction with hydrochloric acid} \\ \hline \text{Aluminium} & 660 & 2.7 & \text{reacts rapidly} \\ \hline \text{Copper} & 1083 & 8.9 & \text{no reaction} \\ \hline \text{Nickel} & 1455 & 8.9 & \text{reacts slowly} \\ \hline \text{Tin} & 232 & 7.3 & \text{reacts slowly} \\ \hline \text{Titanium} & 1668 & 4.5 & \text{no reaction} \\ \hline \text{Zinc} & 420 & 7.1 & \text{reacts vigorously} \\ \hline \end{array} MetalAluminiumCopperNickelTinTitaniumZincMelting point (∘C)660108314552321668420Relative density2.78.98.97.34.57.1Reaction with hydrochloric acidreacts rapidlyno reactionreacts slowlyreacts slowlyno reactionreacts vigorouslyUse the information in the table to answer the following questions:
(i) Which metal in the table could be used to make a probe with the lowest density?
(ii) Why would this metal be unsuitable for the probe's outer structure?
Tin is commonly used in electrical solder. Why would tin not be suitable for use in the electrical connections of this probe?
Choose a metal from the table that would be the most suitable for making the structural hull of the probe. Give two reasons for your choice.
