For each trial, compute the mol of titrant; (molarity x L) and keep the number of significant figures to 4.

Trial 1: 12.49 mL =
mol NaOH
Trial 2: 12.32 mL =
mol NaOH
Trial 3: 11.87 mL =
mol NaOH

Trial     Number of moles

  1          0.001249mol

  2         0.001232mol

  3          0.001187 mol

Explanation:

To calculate the number of moles of tritant you need its molarity.

Since the molarity is not reported, I will use 0.1000M (four significant figures), which is used in other similar problems.

Molarity is the concentration of the solution in number of moles of solute per liter of solution.

In this case the solute is NaOH.

The formula is:

Solve for the number of moles:

Then, using the molarity of 0.1000M and the volumes for each trial you can calculate the number of moles of tritant.

Trial    mL           liters          Number of moles

1          12.49       0.01249        0.01249liters × 0.1000M = 0.001249mol

2         12.32      0.01232         0.01232liters × 0.1000M = 0.001232mol

3          11.87       0.01187         0.01187liters × 0.1000M = 0.001187 mol

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.