An element has two naturally occurring Isotopes. The mass numbers of these isotopes are 109.00 u and 111.00 u, with natural
abundances of 20% and 80%, respectively. Calculate its average atomic mass, Report your answer to 2 decimal places.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

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.

it is a solid

explanation:

the pseudoscience are like beliefs, theories, or like practices that are considered scientific