CDS GK Questions 2026

Three parts of oxygen-16 and one part of oxygen-18 give an average of (3 × 16 + 1 × 18) ÷ 4 = 66 ÷ 4 = 16.5 u. Isotopes are atoms of the same element with the same atomic number but different mass numbers, because they have different numbers…

In boiling, bubbles of vapour form throughout the liquid; in evaporation, only molecules at the surface escape.

The All Parties Conference of 1928 set up a committee under Motilal Nehru, and its draft constitution is known as the Nehru Report.

Gypsum (calcium sulphate dihydrate) is not a raw material for glass; it is added to cement to slow down its setting.

Severability is a doctrine used by courts to interpret laws, not a writ. Under Article 32 the Supreme Court, and under Article 226 the High Courts, can issue five writs: habeas corpus, mandamus, prohibition, certiorari and quo warranto.

Bacteria turn the lactose in milk into lactic acid, a new substance, so souring is a chemical change that cannot be reversed.

One kilowatt-hour is the energy used by a 1 kW appliance running for one hour: 1000 W × 3600 s = 3.6 × 10⁶ J. The joule is too small for household bills, so electricity companies charge in kilowatt-hours, commonly called units.

The rocky planets are dense, the gas giants are light, and Saturn is the least dense planet of all. Earth is the densest planet in the Solar System at about 5.5 g/cm³, with Venus close behind at about 5.2 g/cm³; both are made of rock and metal.

This is the thermite reaction, which is highly exothermic: it gives out so much heat that the iron formed comes out molten.

Article 191(1)(a) disqualifies a person who holds an office of profit under the Government of India or the Government of any State.

X-rays have wavelengths from about 0.01 nm to 10 nm, so 1 nm lies well inside the X-ray band. In the electromagnetic spectrum, wavelength decreases from radio waves through microwaves, infrared, visible light and ultraviolet to X-rays and gamma rays.

Dadabhai Naoroji founded it in London in 1866 to put the Indian point of view before the British public and Parliament.

The element with atomic number 8 is oxygen, which gains two electrons to complete its octet and forms sodium oxide, Na₂O. Oxygen's electrons are arranged as 2, 6, so it needs two more to reach the stable arrangement 2, 8 of neon.

Chemical energy is the energy stored in the bonds that link atoms together in molecules. When a chemical reaction breaks old bonds and forms new ones, this stored energy is released or absorbed.

This statement is wrong: soda glass is the soft glass, while pyrex is a hard borosilicate glass. Ordinary soda-lime glass is made from silica (sand), sodium carbonate and limestone; it softens at a fairly low temperature and is used for windows, bottles and tumblers.

Article 231 lets Parliament, by law, set up a common High Court for two or more States, or for two or more States and a Union Territory.

The exosphere, the outermost layer of the atmosphere, is made up mostly of the two lightest gases, hydrogen and helium.

It comes from the Directive Principles of State Policy, which no court can enforce. Article 39(a) asks the State to direct its policy towards securing that citizens, men and women equally, have the right to an adequate means of livelihood.

Crude petroleum is a mixture of hydrocarbons with different boiling points, and fractional distillation separates them. In a refinery, crude oil is heated to about 400 °C and its vapour enters a tall fractionating column that is hot at the bottom and cooler towards the top.

The Quaternary, the latest period of the Cenozoic era, is divided into the Pleistocene and the Holocene epochs. The Quaternary began about 2.58 million years ago.