Which of the following is an example of a physical change? a) ice melting b) rust on a nail c) both d) neither

Rust on a nail is a chemical change.

Ice melting IS a physical change. Ice is made of water, when you melt ice its still water. Just in a different physical state.

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.