Answer:
35.4528731 amu
Explanation:
To appropriately get the atomic mass unit of chlorine, we can get the answer using the masses from the isotopes. This can be obtained as follows. What we do is that we multiply the percentage compositions by the masses.
Now let’s do this.
[75.77/100 * 34.969] + [24.23/100 * 36.966]
= 26.4960113 + 8.9568618 = 35.4528731
Explanation:
A chemical reaction is defined as the reaction in which bonds between the reactants either break or form which leads to the formation of a new substance.
For example, 
So, when we drop a sodium metal into water then it produces a frizzing sound which shows the metal is reacting with water.
We know that when two aqueous solutions chemically react with each other then it may lead to the formation of an insoluble substance which is known as precipitate.
This means that formation of a precipitate is also a chemical reaction.
Thus, we can conclude that following are the statements which show evidence for a chemical reaction.
- Dropping sodium metal into water produces fizzing.
- Mixing two aqueous solutions produces a precipitate.
<h2>Hey There!</h2><h2>_____________________________________</h2><h2>Answer:</h2>

<h2>_____________________________________</h2><h2>CALORIMETER:</h2>
Calorimeter is device used for the measurement of heat. In a calorimeter we can use the temperature change of water to quantify an amount of heat. A calorimeter just captures all the energy released (or absorbed) by a reaction in the water. So Option A and B are wrong as calorimeter don't have anything to do with providing the heat or letting the the heat in, as it is the insulated calorimeter too.
<h2>_____________________________________</h2><h2>Energy in the reaction:</h2>
In the formation of any bond there is equal amount of heat required as to break that bond. It means Energy released in the making of bond is equal to the energy required in the breaking of the bond. So Option D is wrong as it says we need more energy in making then breaking.
<h2>_____________________________________</h2><h2>Enthalpy:</h2>
Enthalpy is the total heat content of the system. As we provide energy to the reactants and the product is formed, so The enthalpy(heat content) of product is more than the Enthalpy of the reactant, Thus Option C is correct.
Enthalpy is denoted by H or Q, its formula is,
H = U + PV
Where,
U is internal energy
PV is equals to Work done ; P = Pressure, V = Volume
<h2>_____________________________________</h2><h2>Best Regards,</h2><h2>'Borz'</h2><h2> </h2>