If 2g of water is at 1C and a copper block at 3C is added to it, and the finall tempertature of mixture is 7 C , what is the mass of the copper?

The APA rule for numbers is that you should begin a sentence with a word even if the number is greater than nine, and the word "percent" should also be used.

Explanation:

i believe it is c.) 1575 j.

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.