How do you find the mass number of an element

Explanation:

The mass number is a specific property of the atoms, defined as the sum of the protons and neutrons, which are the subatomic particles that are in the nucleus of the atom.

The electrons do not count for the mass of atoms because their mass is about 1/1840 the mass of a proton or a neutron.

The relative masses of protons and neutrons is 1: 1, then they count equally.

As an example, the mass number of the atom carbon-12 is calculated in this way:

The number 12 added to the name in carbon-12, stands for its mass number.

Also, the mass number is indicated as a superscript to the left of the chemical symbol of the element, and the atomic number as a subscript to the left of the chemical symbol. For the example of carbon-12 that is:

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 :

increased stability in the completion of fluorine's outer shell.