3 Calculate the amount of heat produced when 52.4 g of methane, CH4,
burns in an excess of air, according to the following equation. CH4(g) +
202(g) — CO2(g) + 2H20(1) AH = -890.2 kJ. a) Is the reaction endothermic
or exothermic? b) Is the energy of the reactants greater than or less than
the products? c) How much heat in kJ is produced in the reaction when
52.4 g of methane is burned?

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.