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.

answer: a tank of height h is filled with water and sits on the ground. water squirts from a hole at a height y above the ground and has a range r. for two y values, 0 and h, r is zero. determine the value of y for which the range will be a maximum.

explanation:

he uptake of drugs from the intestine is often strongly influenced by diffusion. for example, consider a water-insoluble steroid for treating inflammation that is solubilized in aggregates of detergent molecules, called micelles. these micelles, aggregates of 80 soap molecules, have a molecular weight of 24,000, a diameter of 2.6 nm, and a charge of -27. the positively charge ions (counterions) in this system are na".