Explanation

Elements like Cr (24), Cu (29), and Mo (42) show irregular configurations due to extra stability of half-filled or fully filled d-orbitals.

Examples:

• Cr: [Ar] 3d⁵ 4s¹
• Cu: [Ar] 3d¹⁰ 4s¹
• Mo: [Kr] 4d⁵ 5s¹

Explanation

Pyridine has a lone pair on nitrogen that is not involved in resonance, making it readily available for donation.

In aniline and phenol, lone pairs are delocalized into the aromatic ring, reducing basicity.

Explanation

o-Nitrophenol is more acidic due to the strong electron-withdrawing effect of the nitro group and possible intramolecular hydrogen bonding, which stabilizes the conjugate base.

Though both have -NO₂, the ortho position enhances acidity more than the para position.

Explanation

Aldol condensation requires at least one α-hydrogen (hydrogen on the carbon next to the carbonyl group).

Benzaldehyde and formaldehyde lack α-hydrogens, so they cannot undergo Aldol condensation.

Explanation

She directed us to keep quiet over there.

Imperative sentences in indirect speech use verbs like told, ordered, directed + to-infinitive.

"Here" changes to "there" in indirect speech.

Explanation

The sentence describes two past actions; the earlier action ("he left") uses Past Perfect Tense → had left.

The second action ("I came") is in Simple Past.

Explanation

Sabin vaccine is the oral polio vaccine (OPV) developed by Albert Sabin.

It contains live attenuated poliovirus.

It helps in building immunity against poliomyelitis.

Explanation

Dinoflagellates do have cellulose plates, but not impregnated with calcium — that’s a feature of some other protists, not typical dinoflagellates.

They are mostly unicellular and can form blooms (like red tides).

Explanation

ATP (Adenosine Triphosphate) stores and transfers energy released in catabolism to drive anabolic reactions.

It acts as the main energy currency of the cell.

Explanation

A virus consists of a protein coat (capsid) that surrounds its genetic material (DNA or RNA).

It lacks cellular structures.

It is not considered a complete cell.