Which of the following elements would most likely become a positive ion when forming a chemical bond?
a. sulfur
b. helium
c. carbon
d. calcium

correct option will D.

Explanation:

Calcium belongs to the group 2 i.e. of alkaline earth metals in periodic table. electronic configuration of calcium is .

So in order to attain noble gas configuration calcium will loose its two electrons during chemical bond formation.

Sulfur is a non metal which forms negatively charged ion so as to complete ts octet during chemical bond formation.

Helium is a noble gas with fully filled electronic configuration.

Carbon forms bond which is covalent in nature.

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.