Answer:
3. 76 g/ml^3
Explanation:
We are given the mass of the metal pellets which is 33.4 grams. To calculate the density of the metal, we need to divide the mass by the volume. The volume of the metal is not directly given so we need to find it ourselves. The water was initially 12.7 ml and then it rose to 21.6 ml after placing the metal pellets. This indicate that the volume of the metal pellets is 8.9 ml.

We can now use the density formula.



The balanced chemical reaction is:
Zn + 2AgNO3 = Zn(NO3)2 + 2Ag
To determine the amount of the reactant left, we have to determine which is the limiting and the excess reactant. We do as follows:
5.65 g Zn ( 1 mol / 65.38 g) = 0.09 mol Zn
21.6 g AgNO3 (1 mol / 169.87 g) = 0.13 mol AgNO3
The limiting reactant would be silver nitrate since it is consumed completely in the reaction. The excess reactant would be zinc.
Excess Zinc = 0.09 mol Zn - (0.13 / 2) mol Zn = 0.025 mol Zn left
The mineral that is the hardest known substance in nature is a diamond.
Hope this helps.