Copper is a good conductor of heat and electricity so it will not fry easily
I would go with C, because you would always start with products and end with reactants.
To solve this questions you first need to find the number of moles of barium phosphate you have. The molar mass of barium phosphate is 601.93g/mol.
24.4/601.83 = 0.0402 moles barium phosphate
Then you need to use avagadro’s number, 6.022 x 10^23, which is the number of molecules or formula units in a mole.
6.022 x 10^23 * 0.0402 = 2.42 x 10^22 formula units