What is the frequency of a photon whose energy is 5.4 ´ 10-19 J?  (h = 6.626 ´ 10-34 J·s)

8.15 x 10¹⁴Hz

Explanation:

Given parameters:

Energy of photon  = 5.4 x 10⁻¹⁹J

h = 6.626 x 10⁻³⁴J.s

Unknown:

Frequency of the photon = ?

Solution:

The energy of a photon is given as;

          E = hf

h is the Planck's constant

f is the frequency

     f  =   =   = 8.15 x 10¹⁴Hz

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

that's what i got you can count the number of atoms