Voltaic cells produce a positive overall cell potential. what does this indicate?

A positive overall cell potential indicates that reaction will be spontaneous. There is a connection between the Gibbs free energy change (ΔG) and the overall potential:

ΔG = -nFE

where: n - the number of changed electrons, F - Faraday constant, E - the overall potential.
In order for a process to be spontaneous, the Gibbs free energy change has to be negative, and the above relation indicated that the overall potential has to be positive (since the number of electrons and Faraday constant have positive value). 

Evaporation: this is when warmth from the sun causes water from oceans, lakes, streams, ice and soils to rise into the air and turn into water vapour (gas). water vapour droplets join together to make clouds! condensation: this is when water vapour in the air cools down and turns back into liquid water.

Hydrogen is the most abundant element on the periodic table..hope it .