Explanation

Back e.m.f (electromotive force) is the voltage opposing the applied voltage, commonly seen in motors and inductive circuits.

When back e.m.f = 0, there is no opposing voltage, so the entire applied voltage appears across the circuit's resistance.

From Ohm's Law:

I=V−back e.m.f​/R

If back e.m.f = 0, then

I=V/R​(maximum possible current)

Explanation

Electronic transitions occur when electrons jump between energy levels in an atom.

These transitions typically release photons in the infrared, visible, or ultraviolet regions — depending on the energy difference.

γ-radiations (gamma rays) are high-energy photons emitted from the nucleus, not from electronic transitions.

They are associated with nuclear reactions, not electronic energy level changes.

Explanation

In projectile motion, the velocity is maximum at the point of projection and just before hitting the ground,

Because that’s where the full initial speed is present (both vertical and horizontal components).

At the highest point, the vertical component becomes zero,

And only the horizontal velocity remains, so the overall speed is less than at the point of projection.

Explanation

Chlorophyll a is the primary pigment essential for photosynthesis.

It is found in all photosynthetic organisms except bacteria.

It plays a central role in capturing light energy and converting it into chemical energy.

Explanation

In projectile motion, the vertical velocity changes due to gravity.

It increases downward and decreases upward, so it varies at every point.

Explanation

In Adiantum (a type of fern), the annulus is a specialized ring of thick-walled cells that helps in spore dispersal.

It typically occupies ¾ of the edge of the capsule, aiding in the dehiscence mechanism.

Explanation

 The decomposition of dinitrogen pentoxide (N2O5) as shown in the reaction 2N2O5 → 2N2O4 + O2 is a first-order reaction.

This means the rate of the reaction is directly proportional to the concentration of N2O5. 

Explanation

CMYK (Cyan, Magenta, Yellow, Black) is the standard color model used in color printing.

These four inks are combined in layers to produce a wide range of colors on paper.

Explanation

The majority carriers in a p-type semiconductor are holes. 

When a semiconductor material is doped with trivalent impurity atoms (like Boron), it creates "holes" where electrons are missing, effectively giving a positive charge.

These holes then become the majority charge carriers, meaning they are the primary contributors to electrical current flow in the material. 

Explanation

In tracheophytes (vascular plants), the male gametophyte develops from a microspore, forming a microgametophyte (pollen grain).

The microgametophyte produces male gametes (sperm cells) for fertilization.