why sattalites falls on earth after orbitting around it 4 certain years and why specially in the Pacific Ocean

Also wt decides the lifespam of a sattalite???

Satellites have to maintain a certain speed to remain in orbit. There is no reason for why they always fall in the pacific ocean

Well, this is common sense that after flying a geosynchronous orbit the satellites lose energy or battery power and therefore cannot maintain orbit after a certain number of years then they come crashing into the earth.

As for the Pacific Ocean, the satellite crashes there because the Pacific Ocean is a lot bigger than all the other oceans and they choose it because you don't want it crashing into major populated cities. There are only islands and the vast ocean is where you want the satellite to fall.

The lifespan of the satellite depends on how much energy or battery life that the satellite has.

Satellites in very low orbits are still in the thinnest parts of the upper atmosphere. It is so thin that it seems to be a perfect vacuum, but there is still enough gas to make a small drag force on the satellite, so it eventually slows down enough to fall out of orbit. The higher the initial orbit, the less drag and the longer it takes to slow down. Geostationary satellites are so high that they never come down, they just get old, batteries die, thruster fuel runs out so they can't maintain station or pointing angle for their antenna, and they just stop operating. But they stay in orbit, inoperative.

Satellites fall all over the world, but if the operator knows they are about to loose control of a satellite, due to it having lost too much speed or some mechanical problem that is getting worse, they will deliberately steer it to a reentry that results in falling in the middle of the ocean to avoid harming people on the ground.