Freidal craft reaction is the attack of a carbon or carbon chain on aromatic ring with the help of anhydrous AlCl3 to produce alkylated benzene ring.
Only ketone not be able to undergo friedal craft reaction as, it is not aromatic compound whereas all the given reactants are aromatic and gives friedal craft reaction.
Chlorine.
If you search Google images for "Aufbau principle periodic table," you'll find some handy diagrams that will make it much easier to determine an element based on its electron configuration. Determine the number of electrons in the last part of the configuration (in this case, 5), locate that group on the Aufbau periodic table diagram, then count that number from left to right within that group. In this case, within the "3p" portion of the Periodic table, count to 5 and you'll find Chlorine as the answer.
D is the correct answer
every other option contains an element
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>.