1. The reaction for this would be:
Sn + 4 HNO₃ → SnO₂ + 4 NO₂ + 2 H₂O
The first observation would be bubbling of the solution and brown acrid smoke is produced due to the presence of NO₂ gas. Another observation would be the presence of a white solid which is SnO₂.
2. Heating was required to get rid of the H₂O. When all moisture is gone, you weigh the sample. Afterwhich, you further heat it to get ride of the oxygen. By doing this, you would know the individual mass of each element. Then, you can solve for the empirical formula of the oxide of tin.
Answer:

Explanation:
Hello.
In this case, taking into account that HCl has one molecule of hydrogen per mole of compound which weights 36.45 g/mol, we compute the number of molecules of hydrogen in hydrochloric acid by considering the given mass and the Avogadro's number:

Now, from the 180 g of water, we see two hydrogen molecules per molecule of water, thus, by also using the Avogadro's number we compute the molecules of hydrogen in water:

Thus, the total number of molecules turns out:

Regards.
Carbon dioxide (CO2)
in the process of respiration, oxygen and glucose react to form carbon dioxide and water.
Warmer air is less dense than cold air.As air warm it rises while the cold air sink. Warmer air masses forces the cooler air to move which causes wind. These is illustrated when you open a hot oven the hotter air inside the oven rises into cooler air outside the oven.
Answer:
9.6 mol AgCl2
Explanation:
You have to use Avogadro's number: 6.023 x 10^23
5.78 x 10^24 molecules (1 mol AgCl2/ 6.023 x 10^23 molecules) =9.6 mol AgCl2