Light with 4.5 eV of energy hits a metal surface with a work function of 3.2 eV. Will electrons be emitted ? If so how much energy ?

Yes, electrons with energy of 1.3ev will be emitted from the metal surface

Explanation:

From Eisenstein's photoelectric equation;

KE= E - Wo

Where;

KE= kinetic energy of the emitted photoelectron = ??

E= Energy of the photon =4.5 ev

Wo= work function of the metal = 3.2ev

KE= 4.5 ev - 3.2 ev

KE= 1.3 ev

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.