Explanation

The magnitude of the current in metals being proportional to the potential difference across it, as long as the temperature of the conductor is kept constant, is known as Ohm's Law.

This law is expressed mathematically as V= I⋅R, where V is voltage, I is current, and R is resistance.

Explanation

When carboxylic acids are heated with alcohol in the presence of sulfuric acid, the reaction forms esters through a process known as esterification.

Sulfuric acid acts as a catalyst, facilitating the reaction between the acid and alcohol.

Explanation

The correct ascending order of reactivity of alkyl halides is F, Cl, Br, I, with fluorine being the least reactive and iodine being the most reactive.

Reactivity increases down the group as bond strength decreases.

Explanation

In human myelinated fibers, nerve impulses travel at 100-120 meters per second.

Myelination increases conduction speed by allowing the impulse to jump between nodes of Ranvier in a process called saltatory conduction.

Explanation

Fluid secreted by Sertoli cells provides liquid medium, protection, and nourishment to sperms.

These cells support sperm development during spermatogenesis in the testes.

Explanation

Based on the statements:

• Since some tools are useless things and all useless things are trash, it follows that some tools must be trash.
• Conclusion I cannot be confirmed as we do not know if any hammers fall into the category of tools that are trash.
• Conclusion III is false because not all useless things are tools.

Thus, only II is necessarily true.

Explanation

The pattern follows a decrease by two positions in the alphabet for each letter:

• J → H → F → D
• E → E → E → E (constant)
• Q → O → M → K

So, the next term is DEK.

Explanation

Statement III is correct because the passage mentions the Indus River Dolphin. 

Statements I and II are not accurate based on the passage, as it does not state that Pakistan is a "rich country" or that "people from all nationalities" live there.

Explanation

• P is 2 (the smallest non-negative even number).
• Q is 9 (the largest odd number).
• R is 5.

So, (P + Q + R) = 2 + 9 + 5 = 16.

Explanation

The correct answer is: X is 13, Y is 21, Z is 22.

• X is 13 because it is the smallest prime number greater than 11.
• Y is 21 because it is the largest number divisible by 3 that is less than 24.
• Z is 22 because it is the smallest number divisible by 11 that is greater than 11.