Answer:
Following are the response to the given question:
Explanation:
The number of shells
n = 4
Calculating the spectral line:

Answer:
Double replacement reaction.
Explanation:
The Na and Ag atoms both (double) trade places (replacement) with each other.
Answer: Exothermic reaction
Explanation:
Exothermic reactions lose energy, or ΔH, when they react.
When you heated the can with the bit of water inside and you boiled it over a flame, the water turned to vapor (gas) and the pressure in the inside of the can is different from the pressure on the outside of the can. When you placed the can into a ice water beaker or a container, the can shrunk it's size, decreasing it's mass and density. The can shrunk as a result of the inside pressure being equalized with the outside pressure.
The part where you placed it in the ice bath or container was when the water vapor was forced out of the can.