Pure sodium metal explodes when it makes contact with water. in its natural state, chlorine is a deadly, poisonous gas. when these two chemicals combine, they form a harmless, white powder known as sodium chloride or table salt. which of the following statements does this information support? a. the properties of substances change during chemical reactions but then later go back to their original condition. b. heat must be added in order to change the chemical properties of substances. c. when substances are chemically combined, the properties of the new substances that are formed are often different from the properties of the original substances. d. when substances are chemically combined, the properties of the new substances that are formed are the same as the properties of the original substances.

i think it's d but i'm not sure

 C. When substances are chemically combined, the properties of the new substances that are formed are often different from the properties of the original substances

Explanation: In chemical reactions, the substances combine and undergo rearrangement to form new substances and the new substances formed have different properties than the combing substances.

In the given chemical reaction, Na in solid state and a reactive metal combines with gaseous and poisonous chlorine but in stable form to give sodium chloride which is salt and is non toxic.

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.