How much water can be heated by 10 degrees Celsius, giving it 84 kJ of heat.

Answer: 2 kg.
Explanation of the solution: to solve this problem, you must use the formula:
Q = c * m * (t2-t1), where c is the specific heat capacity of water, c = 4200 J / (kg * C); m is the mass of water; (t2-t1) – temperature change, (t2-t1) = 10 degrees C; Q is the amount of heat, Q = 84 kJ = 84000 J.
Substitute the known values into the formula:
m = Q / (c * (t2-t1)) = 84000 / (4200 * 10) = 2 kg.