How many sigma and pi bonds are there in phenol?

In the most simple phenol, 
sigma bond = 7
pi bond = 3

Higher classes of phenol may have more number of bonds. so, don't confuse from that!

Hope this helps!

They are all decomposition reactions.

Firstly, the water in the dams hold gravitational potential energy as they are above ground level. the gravitational potential energy is then transferred to kinetic energy as it falls, spinning the turbinethe turbine then spins the generator, which is a large magnet surrounded by metal coils. by doing this, the generator generates electricity. in this action, the energy transfer taken place is kinetic to electric energy