Explanation

Activation energy is the minimum energy needed to start a chemical reaction by breaking bonds in reactants.

It determines reaction rates (lower = faster).

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

The cochlea is a spiral, snail-shaped structure in the inner ear responsible for converting sound vibrations into nerve signals.

It plays a key role in the sense of hearing.

Explanation

To find the equilibrium constant (Kc) for the reaction H₂ (g) + I₂ (g) ⇌ 2HI (g), we use the formula:

Kc = [HI]² / [H₂] [I₂]

Given concentrations:

[HI] = 0.08 mol/dm³

[H₂] = 0.04 mol/dm³

[I₂] = 0.04 mol/dm³

Kc = (0.08)² / (0.04 × 0.04)

= 0.0064 / 0.0016

= 4

Explanation

Spring potential energy is given by U = 1/2kx².

If stretching to distance S gives 10 J, then to stretch to 2S, the energy becomes 1/2k(2S)² = 4×10 = 40 J.

So, additional work =  40−10 = 30 J.

Explanation

Copper, silver, aluminum, gold, steel, and brass are common conductors of electricity.

The most highly conductive metals are silver, copper, and gold

Silver is the first-best conductor of heat.

Copper is the second-best conductor of heat.

Explanation

The relation between work (W) done and torque (τ) in rotational motion is:

W = τdθ

Where:

- W is the work done

- τ is the torque

- dθ is the angular displacement

This shows that work done in rotational motion is the product of torque and angular displacement.

Explanation

The microscopic form of Ohm's law is:

J = σE

where J is the current density.

σ is the conductivity.

E is the electric field.

Explanation

Kala azar (also known as visceral leishmaniasis) is caused by the protozoan parasite Leishmania donovani.

It is transmitted to humans by the bite of infected female sandflies.

Explanation

Diffusion is the process where particles move from an area of high concentration to low concentration.

Ink spreads evenly in water due to molecular motion, resulting in uniform distribution.