1. Na3PO4+Mg(NO3)2= NaNO3 + MgPO4
So this is not the answer.
2. Al+CuCl2= AlCl3+ Cu
So this is the answer.
3. Mg+O2= MgO2
So this is not an answer
4. Cl2+KI= KCl+I2
So this is also an answer
Hence B and C are answers
1 mole ----------- 6.02 x 10²³ atoms
? mole ---------- 24.08 x 10²³ atoms
moles B = ( 24.08 x 10²³) x 1 / 6.02 x 10²³
moles B = 24.08 x 10²³ / 6.02 x 10²³
= 4 moles
Answer B
hope this helps!
There is no chemical formula for light energy because light is not a chemical.