When air pressure decreases, the mercury in a barometer
goes down
goes up
stays the same

The mercury in the barometer will go down as there is less air pressing down on the bulb of the barometer to push mercury up.

Explanation:

increasing transnational kinetic energy. because the transnational kinetic energy formula consists of only two variables, mass and velocity, increasing one of those properties is the only way to increase an object's transnational kinetic energy. increases to mass and velocity, however, do not have the same impact.

a.   mass number from atomic number