Sarah and evan are in the same science class. the teacher asks the class to design an experiment to determine the effect of acid rain on limestone. sarah designs an experiment which uses chalk and carbonic acid at a ph of 5.7, because she knows that chalk has the same chemical make-up as limestone and she knows that acid rain is primarily made up of carbonic acid at a ph around 5.7. evan designs an experiment which uses limestone tiles and acid rain collected from the environment. how do these experimental methods compare? a. sarah's experimental results will be easier to predict. evan's results will be impossible to predict since he uses real acid rain. b. sarah's materials are cheaper and easier to obtain, but evan's materials will allow him to better mimic real life. c. evan's experimental design will prevent him from being able to form a logical conclusion, whereas a conclusion can be made with sarah's design. d. evan's experiment can be preformed at any time, but sarah's experiment can only be performed when there is a rainstorm.

Sarah's materials are cheaper and easier to obtain, but Evan's materials will allow him to better mimic real life.

Explanation:

explanation:

the largest database of organic compounds lists about 10 million substances, which include compounds originating from living organisms and those synthesized by chemists. the number of potential organic compounds has been estimated at 1060—an astronomically high number. the existence of so many organic molecules is a consequence of the ability of carbon atoms to form up to four strong bonds to other carbon atoms, resulting in chains and rings of many different sizes, shapes, and complexities. the simplest organic compounds contain only the elements carbon and hydrogen, and are called hydrocarbons. even though they are composed of only two types of atoms, there is a wide variety of hydrocarbons because they may consist of varying lengths of chains, branched chains, and rings of carbon atoms, or combinations of these structures. in addition, hydrocarbons may differ in the types of carbon-carbon bonds present in their molecules. many hydrocarbons are found in plants, animals, and their fossils; other hydrocarbons have been prepared in the laboratory. we use hydrocarbons every day, mainly as fuels, such as natural gas, acetylene, propane, butane, and the principal components of gasoline, diesel fuel, and heating oil. the familiar plastics polyethylene, polypropylene, and polystyrene are also hydrocarbons. we can distinguish several types of hydrocarbons by differences in the bonding between carbon atoms. this leads to differences in geometries and in the hybridization of the carbon orbitals.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.