Will mark ! which balanced equation represents an oxidation-reduction reaction? (explain)

(1) ba(no3)2 + na2so4 ==> baso4 + 2nano3

(2) fe(s) + s(s) ==> fes(s)

(3) h3po4 + 3koh==> k3po4 + 3h2o

(4) nh3(g) + hcl(g)==> nh4cl(s)

(2) Fe(s) + S(s) → FeS(s)

Explanation:

(2) Fe(s) + S(s) → FeS(s).

Fe is oxidized to Fe²⁺ in (FeS) (loses 2 electrons). "reducing agent".

S is reduced to S²⁻ in (FeS) (gains 2 electrons). "oxidizing agent".

The first reaction: (1) Ba(NO3)2 + Na2SO4 ==> BaSO4 + 2NaNO3

is replacement reaction.

The third reaction: (3) H3PO4 + 3KOH==> K3PO4 + 3H2O

is acid-base reaction.

The fourth reaction: (4) NH3(g) + HCl(g)==> NH4Cl(s)

is synthesis reaction.

the only liquid elements at standard temperature and pressure are bromine (br) and mercury (hg). although, elements caesium (cs), rubidium (rb), francium (fr) and gallium (ga) become liquid at or just above room temperature.

explanation:

answer; protein;