12. the number of protons and neutrons tells us:
| a. the principle quantum
number
b. the reactivity of the element e
c. the atomic mass
d. the atomic number
. both a and c

c. The atomic mass

Explanation:

The atomic mass is the total number of protons and neutrons which are present in the atomic nucleus of an element. All atomic nucleus have protons and neutrons except by exception of common form of hydrogen H+.

Mass number or atomic mass = proton number + neutrons number

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 :