A 2.00L mixture of helium, nitrogen, and neon has a total pressure of 815 mmHg at a temperature of 255K. If the partial pressure of helium is 201 mmHg and the partial pressure of nitrogen is 351 mmHg, what is the partial pressure of neon in the mixture?

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

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.