Answer:
4) Each cytochrome has an iron‑containing heme group that accepts electrons and then donates the electrons to a more electronegative substance.
Explanation:
The cytochromes are <u>proteins that contain heme prosthetic groups</u>. Cytochromes <u>undergo oxidation and reduction through loss or gain of a single electron by the iron atom in the heme of the cytochrome</u>:

The reduced form of ubiquinone (QH₂), an extraordinarily mobile transporter, transfers electrons to cytochrome reductase, a complex that contains cytochromes <em>b</em> and <em>c₁</em>, and a Fe-S center. This second complex reduces cytochrome <em>c</em>, a water-soluble membrane peripheral protein. Cytochrome <em>c</em>, like ubiquinone (Q), is a mobile electron transporter, which is transferred to cytochrome oxidase. This third complex contains the cytochromes <em>a</em>, <em>a₃</em> and two copper ions. Heme iron and a copper ion of this oxidase transfer electrons to O₂, as the last acceptor, to form water.
Each transporter "downstream" is <u>more electronegative</u><u> than its neighbor </u>"upstream"; oxygen is located in the inferior part of the chain. Thus, the <u>electrons fall in an energetic gradient</u> in the electron chain transport to a more stable localization in the <u>electronegative oxygen atom</u>.
The charge on Pb in Pb(SO3)2 is Lead (IV) Sulfite.
He is the closest. Then:
Ne, N2, CO, NH3.
NH3 is the least closest to ideal.
hey there!:
H2S(aq) <=> H⁺(aq) + HS⁻(aq)
K'c = [H⁺][HS⁻]/[H₂S] = 9.5*10⁻⁸
HS⁻(aq) <=> H⁺(aq) + S²⁻(aq)
K"c = [H⁺][S²⁻]/[HS⁻] = 1.0*10⁻¹⁹
H₂S(aq) <=> 2 H⁺(aq) + S²⁻(aq)
Kc = [H⁺]²[S²⁻] / [H₂S]
= [H+][HS⁻] / [H₂S] * [H⁺][S²⁻]/[HS⁻]
= K'c *K"c
= ( 9.5*10⁻⁸ ) * ( 1.0 x 10⁻¹⁹ )
= 9.5*10⁻²⁷
Hope this helps!