Here plot in option (A) is correct as kinetic energy of photoelectrons is independent of the intensity of radiation. The highest kinetic energy of the optical electron does not depend on the intensity of incident radiation. The opposing potential changes with the frequency of incident radiation. 

Hence, the correct option is (A).

Ferredoxin (Fd) is comprised of ubiquitous, small proteins containing one or two iron-sulfur clusters. These prosthetic groups contain iron and sulfur atoms, organized in three different types of centers: 2Fe–2S, 4Fe–4 S, and 3Fe–4S. The presence of the cluster(s) confers to the protein the property of absorbing light in the visible region. Fd solutions are thus reddish-brown in the oxidized state and fade upon reduction.

Hence, the correct option is (B).

The alkali metal ion exist as hydrated ions M⁺(H₂O)_n in the aqueous solution. The degree of hydration, decreases with ionic size as we go down the group. Hence Li⁺ ion is mostly hydrated e.g., [Li(H₂O)₆]⁺. Since the mobility of ions is inversely proportional to the size of their hydrated ions, hence the increasing order of ionic mobility is Li⁺ < Na⁺ < K⁺ < Rb⁺

Hence, the correct option is (D).

An analysis of chromosomal DNA using the Southern hybridization technique does not use PCR.

E.M Southern(1979) discovered is a hybridization technique known as Southern blotting for the identification of the particular size of DNA from the mixture of other similar molecules. This technique is based on the principle of separation of DNA fragments by gel electrophoresis and identified by labelled probe hybridization. The various steps involved in this technique are:

• Isolation of DNA
• Digestion of DNA by restriction endonucleases
• Separation of DNA fragments by electrophoresis
• Blotting- transferring separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon
• Hybridisation using labelled VNTR probe
• Detection of hybridised DNA fragments by autoradiography.

Hence, the correct option is (D).

The overall three-dimensional structure of a polypeptide is called its tertiary structure. The tertiary structure is primarily due to interactions between the R groups of the amino acids that make up the protein.Similarly, polar R groups can form hydrogen bonds and other dipole-dipole interactions.

Hence, the correct option is (C).

As the spheres are smooth there will be no friction (no torque) and therefore there will be no transfer of angular momentum.

Thus A, after collision will remain with its initial angular momentum

i.e., ω_A=ω

Hence, the correct option is (C).

In both types of reproduction (asexual and sexual), there is a transfer of genetic material from parent to offspring which have some resemblances with their parents.  Reduction division (meiosis) has to occur if a diploid body has to produce haploid gametes that are in case of sexual reproduction only.  Gametic fusion The formation of male and female gametes and their fusion to form the zygote also takes place only in sexual reproduction.

Hence, the correct option is (C).

An ion exchange resin containing R−COOH group exchange cations like  when hard water is passed through it. This resin is called cation exchange resin.

Hence, the correct option is (D).