Explanation

Phosphorous, especially red phosphorous, is used in the preparation of matchsticks because it ignites easily due to its rapid burning property.

It helps in the quick ignition of the match when struck.

Explanation

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

It contains hair cells that detect sound and send signals to the brain via the auditory nerve.

Explanation

Dispersion occurs when white light passes through water droplets in the atmosphere, causing the light to spread out into its component colors (spectrum).

Each color of light bends by a different amount due to their different wavelengths, resulting in the formation of a rainbow.

Explanation

Opuntia (Prickly Pear Cactus) is a common desert plant adapted to arid conditions.

It has thick, water-storing pads and spines to reduce water loss, making it suitable for desert habitats.

Explanation

Primary pollutants are directly emitted from sources like vehicles and industries (e.g., NO₂, CO, SO₃).

SO₄ (Sulfate) is a secondary pollutant, formed through chemical reactions in the atmosphere.

Explanation

Carpel is the female reproductive part of a flower.

It consists of stigma, style, and ovary, which are essential for reproduction.

It forms the fourth and innermost whorl in a flower's structure.

Explanation

Decomposers break down organic matter into simpler substances.

Bacteria and fungi play a key role in decomposition and nutrient recycling.

Explanation

Since P ∝ 1/V, it means P × V = constant.

So, 10 × 25 = P × 20

Solving:

250 = 20P ⇒ P = 12.5 N/m²

Explanation

When two resistances of 2Ω each are connected in parallel:

1/R = 1/R1 + 1/R2

= 1/2 + 1/2

= 2/2

= 1

R = 1Ω

Explanation

Combustion is a chemical process in which a fuel reacts with oxygen to produce carbon dioxide, water, and energy (usually in the form of heat or light).

It is an exothermic reaction.

It is commonly seen in burning fuels like wood, gas, or coal.