50 pts don't dare to answer wrong or just write irrelevant. answer must be with explanation. would mark brainliest.

Answer/Explanation:

Part 1 and 3: Test tube 4. The hot water and Acid added to the substance makes it much more reactive, which is the reason why the new substance is bubbling. Hot water allows the particles in a chemical reaction have enough force and more chances to go through actual reaction process. This also caused it to create the most bubbles.

Part 2 and 4: Test tube 1 had the least amount of chemical reactivity. Cold water slows down the amount of times a particle in the substance hits another. This reduces the chance of it reacting and the strength of it's reaction. Test tube 1 was also missing the citric acid. Since acids have low pH it is very reactive with other particles with substances that contain less than 8 valence electrons. Without the acid it doesn't have ad much urge to react with. The lower the pH the better reactivity.

while cooking a piece of 1/2 pound beef steak, a cast iron pan (2.4kg in weight) was heated 260 celsius.

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.