Question 3 of 10 The box shows the element helium as it appears in the
periodic table.
2
He
Helium
4.0
Which list gives the correct numbers of subatomic particles for a neutral
atom of helium?
A. Two protons, two neutrons, two electrons
B. Two protons, two neutrons, four electrons
C. Four protons, four neutrons, four electrons
D. Two protons, four neutrons, six electrons

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.

answer: the value of enthalpy change will be -152.80 kj.

solution:

pressure = 1atm , temperature = = 298 k

given that pressure and temperature are same in both gases , the number of moles of both gases can be determined by the ideal gas equation.

according to reaction 3 moles no are reacting with 1 mol of ,then 0.49 mol of no will react with moles of ozone that is 0.16 moles of ozone. since, no is limiting reagent and is an excessive reagent.

enthalpy change for the reaction between the given volumes of the gases is :

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.