Sam wants to know how fast his brother can run. he knows the time it took for his brother to run from the starting line to the finish line. what else does he need to know in order to calculate the speed of his brother? choose all that apply.

he needs to know the direction his brother ran.

he needs to know what time his brother ate lunch.

he needs to know the distance from the starting line to the finish line.

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.  

girl imma just put my comment here because i need a couple point okurrttt

answermeridional ;