How many electrons does a magnesium atom lose when it reacts with an oxygen atom?

a. 3
b. 2
c. 1
d.4

The answer to your question is:  B. 2

Explanation:

Magnesium is located in group IIA, that means that it has 2 electrons in its outermost shell, and these are the electrons that it can lose to become stable.

Oxygen is located in group VI A, that means that it has 6 electrons in its outermost shell and needs to electrons to become stable.

                        Mg⁺²   +  O₂²⁻   ⇒   MgO

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.

gas

explanation:

smoke is the matter of a gas