1. Working in the laboratory, a student find the density of a piece of pure aluminum to be 2.85 g'om? The accepted value for the density of aluminum is 2.699 g/cm? What is the student's
percent error?

5.59 %

Explanation:

From the question given above, the following data were obtained:

Observed value of density = 2.85 g/cm³

True value of density = 2.699 g/cm³

Percentage error =.?

The percentage error of the student can be obtained as follow:

Percentage error = |Observed value – True value|/True value × 100

Percentage error = |2.85 – 2.699|/2.699

Percentage error = 0.151/2.699 × 100

Percentage error = 5.59 %

Therefore, the percentage error of the student is 5.59 %.

i believe the answer is a.

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.