Answer:
When a solid turns to a gas.
Explanation:
Answer:
I would say there would be 5-10% in a city, and maybe 10-20% in the country. It mainly varies depending on how big the city is, how many people/districts there are, and the size of the country, which makes it hard to give a certain percent of shops, as there may be small businesses included as well or new shops being built.
Hope this helps! This was pretty confusing for me as well so i hope the answer is alright (×﹏×)
The average speed is calculated using the following formula
Where

T = 298 K [room temperature]
m = mass of each molecule of oxygen
mass of one mole of oxygen molecules = 32 g / mol
mass of one molecule of oxygen will be = 
mass of one molecule of oxygen will be = 
putting values
average speed = 
Average speed = 482.19 m / s
average speed = 1735.8 km / h
so approx = 1700 km/h