The photoelectric effect is explained by quantum mechanics and particle nature of light, not by wave optics.

Floating of heavy objects is not related to surface tension; it is related to buoyancy. The other phenomena are directly influenced by surface tension.

Capillary action is primarily due to surface tension, as it allows liquids to rise in narrow tubes against gravity.

Refraction is the bending of light as it passes from one medium to another due to a change in its speed.

The blue color of the sky is primarily due to Rayleigh scattering, which scatters shorter wavelengths of light more than longer wavelengths.

The formation of a rainbow is primarily due to the refraction and dispersion of light in water droplets.

Existentialism focuses on individual experience and the subjective interpretation of existence and truth.

The phrase 'the main point' accurately captures the essence of 'the crux of the matter'.

The Chola dynasty is noted for its extensive development of irrigation canals which significantly enhanced agricultural productivity.

Pteridophytes, like ferns, exhibit an alternation of generations with both gametophyte and sporophyte stages.

All of the mentioned groups (Angiosperms, Gymnosperms, and Pteridophytes) exhibit alternation of generations in their life cycles.

The distance from the origin to a point (x, y) is given by √(x² + y²). The point (0, 1) has a distance of 1, which is the smallest.

Substituting (0, -4) into the equation gives 4(0) - 5(-4) + 20 = 0, which is true.

Substituting x = 2 into the equation y = 2(2) + 1 gives y = 5, so the point (2, 5) lies on the line.

Substituting x = 1 into the equation gives y = 1^2 - 4 = -3, so the point (1, -3) lies on the parabola.

Land Reforms were aimed at redistributing land to the landless and ensuring equitable access to resources, thus promoting inclusive growth.

The Doctrine of Lapse was a policy that allowed the British to annex any princely state if the ruler died without a male heir, which contributed to the discontent leading to the Rebellion of 1857.

The Integrated Rural Development Programme was launched in the 1970s to provide employment and promote self-reliance among the rural poor.

Lead is a heavy metal that can be toxic to humans and the environment.

Volatile Organic Compounds (VOCs) are major contributors to smog formation, especially in urban areas.

Ozone at ground level is a major component of smog, formed by the reaction of sunlight with pollutants.

Nitrogen Dioxide is a major contributor to the formation of smog, particularly in urban areas.

Nitrogen Dioxide (NO2) is associated with respiratory problems and is a significant air pollutant.

Nitrogen dioxide is a key contributor to the formation of smog, especially in urban areas.

Sulfur oxides (SOx) and nitrogen oxides (NOx) are the main pollutants that contribute to the formation of acid rain.

A concave hexagon has at least one interior angle greater than 180 degrees, which makes it a non-convex polygon.

A star-shaped polygon has at least one interior angle greater than 180 degrees, making it concave.

Nylon is known for its high tensile strength and is commonly used in textiles and ropes.

Nylon-6,6 is produced by condensation polymerization, involving the reaction of diamines and dicarboxylic acids.

Natural rubber is a polymer made from the latex of rubber trees and is widely used in the production of rubber products.