Question

At 0m (sea level) what is the atmospheric pressure?

Answer 1

By definition it's `1*"atmosphere"`......

Explanation:

Most chemists would use atmospheres to measure pressure, as it is quite an intuitive unit. `"1 atmosphere"` of pressure will also support a column of mercury that is `760*mm` high; and this is a VERY convenient unit for high vacuums and small pressure differences (convenient until you break the mercury manometer and get mercury all over the lab!).

In kilopascals, `1*atm-=101.3*kPa`, where `1*"Pascal"-=1*"Newton"*m^-2`, a force per unit area, a pressure as required.