Dmitri Mendeleev devised the first periodic table.
An oxidation-reduction (redox<span>) </span>reaction<span> is a type of chemical </span>reaction<span> that involves a transfer of electrons between two species. An oxidation-reduction </span>reaction<span> is any chemical </span>reaction<span> in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.</span>
A baseline for experimental investigation is provided by an hypothesis. This is a must before conducting experiments. Also, it is the hypothesis that is being proved by doing the experiments. So, hypothesis is very important in research studies. Hope this answers the question.
Explanation:
Given that,
Mass of metal cube, m = 20 g
Volume of cube, V =5 mL
We need to find the density of the cube. Mass per unit volume equals density.

So, the density of the cube is 4 g/ml.
We know that the density of Aluminium is 4 g/mL.
So, the cube is not Aluminium cube.