Answer:
This happens because the tin is made of estañum, and the estañum is denser than the water.
Remember the relation:
density = mass/volume
The general rule is that if an object is denser than water, it will sink
If an object is less dense than water, like a piece of wood, it will float.
And if an object has the same (or nearly the same) density as water, it will float, but fully submerged.
Based on that, we can conclude that the tin will sink because it's density is larger than the density of the water.
