Scale and measuring tape.
To determine the mass and volume, you can find the density. The block will float if its density is less than that of water.
By 1.23 x 1024 you mean 10 to the power of 24 molecules? If so all you need to do is divide the number of molecules you have by Avagadros number, 6.022 x 10^23. This will give you the mols of water, or the mols of anything, since there is always 6.022 x 10^23 molecules in 1 mol of substance.
1.23x10^24 atoms/6.022x10^23 atom/mol = 2.04 mol H20
The empirical formula of metal iodide : CoI₃(Cobalt(III) Iodide)
<h3>Further explanation</h3>
13.02 g sample of Cobalt , then mol Co(MW=58.933 g/mol) :

Mass of metal iodide formed : 97.12 g, so mass of Iodine :

Then mol iodine (MW=126.9045 g/mol) :

mol ratio of Cobalt and Iodine in the compound :
Heptane means seven carbon atoms and since the general formula is CnH2n+2, heptane will be C7H16
<h3><u>Answer;</u></h3>
It makes the reaction harder to start
<h3><u>Explanation</u>;</h3>
- <em><u>Activation energy is minimum amount of energy that is required for a reaction to start. Activation energy determines the rate of a chemical reaction such that the higher the activation energy, the lower the rate of chemical reaction and vice versa.</u></em>
- The source of activation energy needed to push chemical reactions forward is obtained from the surroundings. Catalyst speed up chemical reaction by lowering the activation energy. Therefore, catalysis is the increase in the rate of a chemical reaction by lowering its activation energy.