D-It was discovered a while ago and it's about 500 light years away from earth
The correct answer would be D. Ca^2+ has 18 electrons. This is because 2+ means that 2 electrons have been removed, and Ca starts out with 20 electrons. As 20 - 2 = 18 electrons, D is the correct answer.
Hope this helps!
Answer:
1-Mg+O2=reactants MgO-product
2-CaNr2+AlCl3=reactants CaCI2+AIBr3=product
3-C2H4+O2=reactants H2O+CO2=product
Explanation:
Reactants are on the left side and products on the right.
Its c ok im sorry if i got the last answer wrong
