4 Select the correct answer.
Which statement best describes how chemical equations demonstrate conservation of mass?
OA.
The number of reactants is the same as the number of products,
OB.
The compounds are the same on each side of the reaction.
O C.
The number of atoms of each element is the same on each side of the equation.
hodation
OD.
The state of matter is the same on each side of the equation,

we need the questions , i may then you.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a

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.