If hydrogen gas and oxygen react with enough of heat they produce steam. a. Write the equation and balance if needed. b. If you have 250 g of steam, how many grams of hydrogen and oxygen were needed to react to produce this amount of steam?

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante

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.