What is the heat of vaporization of water?

The molecules in liquid water are held together by relatively strong hydrogen bonds and its enthalpy of vaporization, 40.65 kJ/mol is more than five times the energy required to heat the same quantity of water from: 0 °C to 100 °C (cp = 75.3 J K−1 mol−1).

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When the ball hit the ground, the height of the ball will be zero. So using the value of h(x) as zero in the given equation, we can find the time in which the ball will hit the ground.

0 = -(x-2)^2 + 16

(x-2)^2 = 16

x-2 = 16

x-2 = 4

x = 6

This means the ball will hit the ground 6 seconds after Amir threw it.