What is the difference in pressure within a fluid at its surface and a distance d below its surface?

The air that we breath is made mostly of which gaseous molecule

If a rock is thrown upward on the planet mars with a velocity of 12 m/s, its height (in meters) after t seconds is given by h = 12t − 1.86t2. (a) find the velocity of the rock after two seconds. m/s (b) find the velocity of the rock when t = a. 12−3.72a m/s (c) when will the rock hit the surface? (round your answer to one decimal place.) t = s (d) with what velocity will the rock hit the surface? m/s

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?