Question

In which place in Russia water ignites, gravity is zero and heavy rocks float on water

Answer 1

Because the Earth’s gravity pulls on the water more than on the wood, so the water ends up closer to the centre of the earth than the wood does.

At least, for wood that is less dense than water. Gravitational attraction (weight) depends on the mass, so for a given size of object, the more massive one will experience more force and will sink compared to the lighter one. See 

Answer 2

Yes, at some place in Russia, rocks float on water, can’t tell the name. What I can tell is in Russian folklore, there is a saying that adder stones float on water.

Also, Pumice stone floats on water. I have seen the video of rocks floating on water. Pumice stones are low in density, and weigh less than pure water, which makes it easier for it to float.

The Pumice rocks may look heavy, but are not and therefore could float. Therefore, Russian rocks might be pumice rocks.