Which are not combination reactions? Check all that apply.
A. 2H2O + 2H2 + O2
B. H2 + Cl2 → 2HCI
C. Fe + MgO + Mg + FeO
D. 2Na + Cl2 → 2NaCl

A and c

Explanation:

In A the product is added to the reactant, so the real reaction is (2H2O = 2H2+O2).

In B hydrogen and clorine are combined to give hydrochloric acid and 2 is used to balance the reaction in the product, so it's a combination reaction .

In C the case is similar to A , so the real reaction is (Fe+MgO = Mg + FeO ) this is displacement reaction where a more reactive element takes place of a less reactive element .

In D sodium reacting with Chlorine to give sodium chloride ,so we conclude that it's a combination reaction .

i believe it is 40–40–20%

explanation:

atomic number of carbon is 6

electronic configuration of carbon is 1s²2s²2p²

orbital diagram of carbon is as shown here in the image.