How many significant figures are in the measurement 0.0003010 kilograms

Which is the layer underground where all empty spaces are filled with a combination of air and water ?

The diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?

What three natural resources are found in the great lakes region