An incandescent 60 W bulb has only a 5% efficiency and uses 600 J of energy in 10 seconds. How much thermal energy is generated by the bulb in 10 seconds

The bulb will  be generate only 30 Joules energy at 10 Second.  

Explanation:

The formula to calculate the total number of Joules of energy by the light bulb is as follows:

E (Joules) = P (Watts)  X  t (seconds)

E = 60 W  X  10 seconds

E = 600 Joules of energy

The total amount of energy generated by the light bulb every 10 Sec is 600 Joules.  If the light bulb is only 5 %  efficient , that would be 5% of the total.

600 J ×= 30 Joules

Of the total energy, the bulb will generate only 30 Joules energy at 10 Second.  

if you mean hydrogen and oxygen then water is the product