Consider the reaction 2H2(g) + O2(g) → 2H2O(g). The following bond energies have been determined experimentally:
H-H 436 kJ/mol
O=O 497 kJ/mol
H-O 464 kJ/mol
Suppose we start with 4 mol of hydrogen and end up with 4 mol of H2O.
If the system was at 300 K before the reaction took place, what is the final temperature after the reaction?

state the principle of separating two immiscible liquids by separating funnel. describe an activity with diagram to separate a mixture of water and kerosene oil. answer: immiscible layers separate out in layers depending on their densities in separating funne

why is arctic sea ice important? arctic sea ice keeps the polar regions cool and moderate global climate. sea ice has a bright surface; 80 percent of the sunlight that strikes it is reflected back into space. as sea ice melts in the summer, it exposes the dark ocean surface.

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.