the empirical formula of c2h4o2
ch2o
c2h4o2
ch4o
c4h8o4

CH2O

Explanation:

the empirical formula of a compound is determined by obtaining the moles of each element and then divided each element by  the lowest value. represents the simplest ratio in which atoms that form a chemical compound.

for the molecular formula C2H4O2; its empirical formula would be:

moles C: 2/2 = 1

moles H: 4/2 = 2

moles O: 2/2 = 1

⇒ empirical formula: CH2O

answer; /// the amount of material dissolved in a measure of liquid(concentration) the above statement is (true); /// good luck

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.