CDS GK Questions 2026

A small quantity of fluoride in drinking water protects teeth against decay, but when the concentration rises above the permissible limit it causes fluorosis.

Water hyacinth is an aquatic weed introduced into India from South America.

The mission, working under the Ministry of Jal Shakti, is the implementing agency of the Namami Gange Programme launched in 2014, and it works through State Ganga Committees and district committees along the river.

The Ganga Action Plan was launched in 1985 to intercept, divert and treat the sewage of the towns along the river, and it was the first programme of its kind in India.

The Water (Prevention and Control of Pollution) Act of 1974 was India’s first comprehensive law on pollution.

When fertilisers, detergents and sewage add nitrates and phosphates to a lake or a slow-moving river, algae multiply into a bloom that covers the surface.

Nitrate from fertiliser run-off and from sewage seeps into groundwater; in an infant it is converted to nitrite, which binds to haemoglobin and forms methaemoglobin, a compound that cannot carry oxygen.

Biochemical oxygen demand measures the oxygen that micro-organisms need in order to break down the organic matter present in a sample.

Minamata disease takes its name from Minamata Bay in Japan, where a factory discharged mercury compounds that were converted by bacteria into methylmercury, concentrated in fish through biomagnification and then eaten by people.

Itai-Itai disease was first identified in Japan among people who ate rice grown with water polluted by cadmium from mining waste.

Only a transverse wave can be polarised, so the polarisation of light proves that its vibrations are at right angles to the direction of travel.

A nuclear reactor splits heavy atoms; it burns no fuel, so it releases no carbon dioxide and needs no equipment to cut such emissions.

It is a sea level canal: the Mediterranean and the Red Sea stand at almost the same height, so ships sail straight through without being raised or lowered.

Bacteria are prokaryotes, so their DNA lies free in the cytoplasm instead of being packed inside a nucleus. The single circular chromosome sits in a region of the cytoplasm called the nucleoid, which has no nuclear membrane around it.

The Ilbert Bill of 1883 sought to remove the rule that European British subjects could be tried only by European judges.

Vinayak Damodar Savarkar founded Abhinav Bharat at Nashik in 1904, together with his brother Ganesh. It grew out of an earlier group called Mitra Mela and took its name from Mazzini’s Young Italy, whose biography Savarkar translated into Marathi.

Baking soda is sodium hydrogen carbonate, NaHCO3, a mild base made by the Solvay process from brine, ammonia and carbon dioxide.

Melting means breaking the particles free of the forces holding them in a fixed lattice, so a higher melting point means stronger forces of attraction.

Asia takes the largest share of India’s exports, close to half of the total, far ahead of any other continent.

Chadwick discovered the neutron in 1932 and won the Nobel Prize in Physics for it in 1935. He bombarded beryllium with alpha particles and found that the radiation given off was not affected by electric or magnetic fields, yet could knock protons out of paraffin.