<u>Answer:</u> The temperature of the solution in Kelvins is 422.356 K
<u>Explanation:</u>
Temperature is defined as the measure of coldness or hotness of a body. It also determines the average kinetic energy of the particles in a body.
This term is expressed in degree Celsius, degree Fahrenheit and Kelvins. All these units are interchangeable.
The S.I unit of temperature is Kelvins.
We are given:
Temperature of a solution = 
Conversion used to convert degree Celsius and Kelvins is:
![T(K)=[273.15+T(^oC)]](https://tex.z-dn.net/?f=T%28K%29%3D%5B273.15%2BT%28%5EoC%29%5D)
Hence, the temperature of the solution in Kelvins is 422.356 K
Unfortunately the data provided doesn't include the DENSITY of the ammonium chloride solution and molarity is defined as moles per volume. So without the density, the calculation of the molarity is impossible. But fortunately, there are tables available that do provide the required density and for a 20% solution by weight, the density of the solution is 1.057 g/ml.
So 1 liter of solution will mass 1057 grams and the mass of ammonium chloride will be 0.2 * 1057 g = 211.4 g. The number of moles will then be 211.4 g / 53.5 g/mol = 3.951401869 mol. Rounding to 3 significant digits gives a molarity of 3.95.
Now assuming that your teacher wants you to assume that the solution masses 1.00 g/ml, then the mass of ammonium chloride will only be 200g, and that is only (200/53.5) = 3.74 moles.
So in conclusion, the expected answer is 3.74 M, although the correct answer using missing information is 3.95 M.
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Out of the options, the best indicator is a color change since it is the only one that can't really be blamed on a physical change. you will eventually notice that during qualitative labs and some quantitative labs, usually the thing that you are looking for is either color change or the production of a precipitate to indicate the presence of a chemical reaction
