I NEED HELP PLEASE! :)

Describe a limiting reactant in your own words.

If the element whose electric configuration ends in the d sublevel, the element is calssified as? a.inner transition b.noble gases c.representative d. transition

Which traits do human embryos have that link them to a common ancestor with fish and reptiles? a. scales and tail b. gill slits and scales c. tail and gill slits d. hair and tail

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