Which of the reactions below is a formation reaction?
1. 4Fe(s) + 3O2(g) → 2Fe2O3(s)
2. Mg(s) + F2(g) → MgF2(ℓ)
3. 1/8 B8(s) + 3/2 F2(ℓ) → BF3(s)
4. H2O(ℓ) + SO3(aq) → H2SO4(aq)

in theory, limestone is composed principally of the compound calcium carbonate - caco3, but in reality this compound is deposited in conditions involving a number of other compounds as impurities so it ends up being a mixture of many compounds.

hope this : -)

tony (lordcaos066)

level 4 to level 2 : ))