Answer:
B
Explanation:
If the temperature of the water goes up, the reaction is exothermic (heat is being given away by the equation -- more precisely the reactants of the equation). Only A and B can be true. In order for the reaction to occur, the water has to absorb the heat. It's temperature goes up. Remember that minus sign. It is almost the key fact for this question.
The question is not as hard as it looks, but that is easy for me to say.
m = 100 g
c = 4.2 J/(g * oC)
deltaT = 21 - 20 degrees = 1 degree.
Heat = 100 * 4.2 * 1
Heat = 420 J
Heat = 420 * [1 kJ/1000 J]
Heat = -0.42 kJ
B
<u>Answer:</u> The entropy change of the liquid water is 63.4 J/K
<u>Explanation:</u>
To calculate the entropy change for same phase at different temperature, we use the equation:

where,
= Entropy change
= molar heat capacity of liquid water = 75.38 J/mol.K
n = number of moles of liquid water = 3 moles
= final temperature = ![95^oC=[95+273]K=368K](https://tex.z-dn.net/?f=95%5EoC%3D%5B95%2B273%5DK%3D368K)
= initial temperature = ![5^oC=[5+273]K=278K](https://tex.z-dn.net/?f=5%5EoC%3D%5B5%2B273%5DK%3D278K)
Putting values in above equation, we get:

Hence, the entropy change of the liquid water is 63.4 J/K
Is that chemistry?
Cause I'm kinda confused about how to help you with this question