Answer:
m = 31.284 grams
Explanation:
Given that,
The dimension of a magnesium block is 2.00 cm x 3.00 cm x 3.00 cm.
The density of magnesium is, d = 1.738 g/cm³
We need to find the mass of the magnesium block. We know that the density of an object is given by its mass per unit its volume. So,

So, the mass of the block is 31.284 grams.
Yes because molecules is solid
Substance a is a base, and substance b is an acid
Litmus is an indicator
Charged particles are ions
Acids contain H+ ions
Bases contain OH - ions
Hydronium ions are H3O+
Now, I have to take issue with the last one
A base of pH 14 is not a strong base, it would be a highly concentrated base. A strong base is a base that completely deionizes in water.
But technically, for the purpose of your answer strong base = pH 14