rust results from iron’s reaction to oxygen. an iron nail gains mass when it rusts. how does this reaction support the law of conservation of mass?

Balance and in which category does it fit in? single or double displacement or synthesis or decomposition? (a) k2 o → k + o2 (b) na + i2 → nai (c) cu(no3 )2 + naoh → cu(oh)2 + nano3 (d) kclo3 → kcl + o2 (e) ca(no3 )2 + hbr → cabr2 + hno3 (f) sn(oh)2 → sno + h2 o (g) p4 + n2 o → p4 o6 + n2 (h) fe + al2 (so4 )3 → feso4 + al (i) alcl3 + na2 co3 → al2 (co3 )3 + nacl (j) c3 h6 + o2 → co2 + h2 o