You would expect a phosphorous-chlorine bond to be
1. nonpolar, with the neither end having a
partial charge.
2. polar, with neither end having a partial
charge.
3. nonpolar, with the chlorine end having a
partial negative charge.
4. polar, with the chlorine end having a
partial negative charge.
5. nonpolar, with the phosphorus end having
a partial negative charge.
6. polar, with the phosphorus end having a
partial negative charge.
explain why

option 4. polar, with the chlorine end having a partial negative charge.

Explanation:

1) A polar bond is a covalent bond in which the electrons are pulled more strongly by one of the atoms and then they are not evely distributed between the two linked atoms.

2) That happens when the two atoms have diferent electronegativities.

3) As the per periodic table trend of the electronegativity, you can predict that the electronetativity of Cl is higher than that of P.

In fact, in a table of electronegativities you can find that the electronegativity of Cl is 3.16 while the electronegativity of P is 2.19.

This is a 3.16 - 2.19 = 0.97 difference.

As explained, that difference means that Cl will pull the electrons more strongly resulting if a partial negative charge on Cl and a partial positive charge on P, i.e. a polar bond.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.