Based on the law of conservation of mass, if approximately 20g of water reacts in the following equation, producing about 15g of oxygen, what mass of hydrogen (H2) was produced in this reaction?
2H20
2H2 + O2

Ahydroelectric plant takes energy from water and turns it into electrical energy. what are the transformations of energy in the water molecules that are used in the process of generating electricity this way?

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

Which of the following list the divisions of the geologic time scale in order from longest to shortest