Liz and Michelle are testing which ball will bounce the highest. They test 4 different balls. Each ball is dropped five times from the same height. The height of the bounce is measured. At the end of the experiment, the data for each ball was averaged to obtain an average bounce height. Is this a well designed experiment?

A)No, it does not give any data.

B)No, they should have used more types of balls.

C)Yes, they tested more than one thing at a time.

D)Yes, they averaged the measurements and had multiple trials.

D

Explanation:,

In designing an experiment there must be multiple trials. Multiple trials eliminate errors when the results are averaged.

This gives better results than when single measurements are used to determine results of experiments. The result of this experiment can be regarded as being reliable because it was well designed.

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.