12. When 5
when 50.0 mL of water con-
raining 0.50 mol HCl at 22.5°C
is mixed with 50.0 mL of
water containing 0.50 mol
NaOH at 22.5°C in a calorime-
ter, the temperature of the
solution increases to 26.0°C.
How much heat (in kJ) was
released by this reaction?

answer; /// i do believe that the correct answer is (a) boiling

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.