How many mol of C2H2 are required to produce 2.50 mol CO2?

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water

Ibelieve the answer is weathering,hope my answer has you : ) 

Deposition  is  change of state has the wrong energy change listed