The element fluorine has 9 electrons. which is the electron configuration for an atom of fluorine?

It is 1s2 2s2 2p2

Explanation:

The ones on the S (sunny side) have 2 arrows going the opposite directions, and the ones on the P (pink side) have arrows going opposite directions also except the one being left out on 2p. I hope this helps and I tried my best explaining the process of it.

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.

the answer is 0.42 is that is an option. this question provides no info