CDS Previous Year GK Questions

A simple periscope has two plane mirrors facing each other in parallel, each tilted at 45° to the tube. Light from the object enters the top opening and strikes the upper mirror, which is set at 45° and turns the light through 90° down the tube.

The 1971 Census recorded a decadal growth of about 24.8 per cent for 1961–71, the highest of any decade in India's census history.

The amara-nayaka system was the main political innovation of the Vijayanagara Empire, under which military commanders were given territories to govern.

This is false, because variations differ in how well they suit the environment, and that difference is the basis of natural selection.

Unsaturated hydrocarbons have a high carbon content and burn with a yellow, sooty flame, while saturated ones usually burn with a clean blue flame.

Milk of magnesia is a suspension of magnesium hydroxide, a mild base that neutralises excess stomach acid without harming the body.

Energy equals power multiplied by time: 0.1 kW × 30 hours = 3 kWh, which is 3 units. The bulb's power is 100 W, which is 0.1 kW.

Chromosomes are made of DNA wound around proteins, mainly histones; together this DNA-protein material is called chromatin. In eukaryotic cells, a very long DNA molecule wraps around groups of eight histone proteins to form beads called nucleosomes.

A qubit, short for quantum bit, is the basic unit of information in a quantum computer, just as the bit is in an ordinary computer.

Chlorophyll is held in the chloroplasts, the green plastids of leaf cells where photosynthesis takes place. A chloroplast is a double-membrane organelle.

The Nilgiri Biosphere Reserve spreads across Tamil Nadu, Kerala and Karnataka, meeting where the Western and Eastern Ghats join. Set up in 1986, the Nilgiri Biosphere Reserve was India's first biosphere reserve and in 2000 became the first in India to join UNESCO's World Network of Biosphere Reserves.

When a conductor moves in a magnetic field and a current is induced in it, this rule gives the direction of that induced current.

HIV infects and destroys helper T lymphocytes, the white blood cells that coordinate the body's immune response, so immunity steadily collapses.

Cancer is uncontrolled cell division that follows the loss of the checks that normally govern growth. Normal cells divide only when signalled and stop when they touch neighbouring cells, a property called contact inhibition.

Blue baby syndrome, or methaemoglobinaemia, strikes infants who drink water with excess nitrate, usually from fertiliser runoff or sewage. In an infant's digestive system, nitrate is converted into nitrite, which oxidises the iron of haemoglobin and turns it into methaemoglobin.

A kelvin and a degree Celsius are the same size, but the Kelvin scale starts at absolute zero, which is −273.15 °C. The kelvin is the SI unit of temperature.

Hydrogen, nitrogen, oxygen and carbon dioxide all exist as gases at about 25 °C and normal atmospheric pressure. Hydrogen boils at about −253 °C, nitrogen at −196 °C and oxygen at −183 °C, so all three are gases at room temperature.

He was called Danka Shah, the drum-beating maulvi, because he moved from place to place with drums announcing his preaching against British rule.

A plane mirror always forms a virtual image, one that cannot be caught on a screen, so calling it real is the false statement.

The tundra is too cold, with a very short growing season and permanently frozen subsoil, for trees to grow, so it has no timber.