Static general knowledge makes up about 90% of Part B of the NDA General Ability Test, about 360 of its 400 marks. The NDA & NA (II) 2026 notice divides it into five sections: Physics (about 25%), Chemistry (about 15%), General Science (about 10%), History, Freedom Movement etc. (about 20%) and Geography (about 20%). Half of Part B is science. Physics covers matter, motion, gravitation, heat, sound, light, magnetism, electricity and the working of everyday devices such as the siphon, pressure cooker, periscope and safety fuse. Chemistry covers changes of matter, elements and compounds, common gases, acids, bases and salts, carbon, fertilizers and the materials used to make soap, glass, cement and gunpowder. General Science covers cells, the human body, diseases, diet, the solar system and eminent scientists. Section D spans Indian history and culture, the freedom movement, the Constitution, Five Year Plans, Panchayati Raj and world history from the Renaissance to the Russian Revolution. Geography covers the Earth, rocks, oceans, the atmosphere and climate, and India's resources, industries, ports and trade. This page holds GK24's topic-wise GK notes for NDA, in English and Hindi, written as short facts and tables. Read a topic, then solve its quiz and previous-year questions on this site.
Water has its maximum density at which temperature?
Water contracts as it is cooled to four degrees, is densest at that temperature, and then expands again as it cools further to zero, which is called the anomalous expansion of water.
Read the full explanation →The temporary hardness of water is caused by the presence of:
These bicarbonates are formed when water containing dissolved carbon dioxide passes over limestone, and they are unstable; on boiling they lose carbon dioxide and settle as insoluble carbonates, which is why this kind of hardness is called temporary and can be removed by boiling alone, or by the Clark method…
Read the full explanation →Heavy water is chemically known as:
Heavy water is D2O, in which both hydrogen atoms are deuterium, the isotope whose nucleus has one proton and one neutron, so its molecular mass is twenty instead of eighteen.
Read the full explanation →Zero hardness of water is achieved by
In an ion exchange plant the water passes through a cation resin, which takes up the calcium and magnesium ions, and then through an anion resin, which takes up the sulphate, chloride and bicarbonate ions; because the hardness-causing ions are actually taken out of the water, the hardness can be…
Read the full explanation →Why is the efficiency of every real machine less than one hundred per cent?
In every real machine some of the work put in is used in overcoming friction between the moving parts and in lifting the parts of the machine itself, and that work leaves the system as heat and sound, so the work delivered to the load is always less than the…
Read the full explanation →Which of the following is an example of a wedge?
A wedge is two inclined planes joined back to back, and an axe, a knife, a chisel and a nail all work on that principle: a force applied at the blunt end is turned into a much larger sideways force at the sharp edge, and the thinner and longer the…
Read the full explanation →The distance between two consecutive threads of a screw is called its:
The pitch of a screw is the distance between two consecutive threads measured along its axis, and it is also the distance through which the screw advances in one complete turn; the velocity ratio of a screw is the circumference of the circle described by the handle divided by the…
Read the full explanation →An inclined plane is 10 metres long and 2 metres high. What is its velocity ratio?
The velocity ratio of an inclined plane is the length of the slope divided by its vertical height, because the load is pushed along the whole slope while it is raised only through the height; here ten divided by two gives five, so in the ideal case an effort of…
Read the full explanation →What is the velocity ratio of a single fixed pulley?
In a single fixed pulley the rope that is pulled down moves exactly as far as the load rises, so the distance moved by the effort equals the distance moved by the load and the velocity ratio is one; the pulley gives no gain in force and is used only…
Read the full explanation →A pair of forceps or sugar tongs is an example of which class of lever?
In a pair of tongs the joint is the fulcrum, the hand presses somewhere in the middle of the arms and the object held lies at the far end, so the effort is between the fulcrum and the load; the effort arm is shorter than the load arm, the mechanical…
Read the full explanation →A wheelbarrow is an example of which class of lever?
In a wheelbarrow the wheel acts as the fulcrum, the load sits in the tray between the wheel and the hands, and the effort is applied at the handles, which is the arrangement of a second class lever; because the effort arm is always longer than the load arm, its…
Read the full explanation →Which of the following mechanical devices efficiently distributes or multiplies loads with little effort?
A lever is a rigid bar turning about a fulcrum, and by the principle of moments the load multiplied by the load arm equals the effort multiplied by the effort arm, so a long effort arm lets a small effort balance a large load; this is the simplest way of…
Read the full explanation →The velocity ratio of a simple machine is the ratio of distance travelled by the ________ to the distance travelled by the ________ in the machine.
Velocity ratio is defined as the distance moved by the effort divided by the distance moved by the load in the same interval of time, and because it depends only on the design of the machine it does not change with friction, unlike the mechanical advantage.
Read the full explanation →Find the efficiency of a pulley system which has a mechanical advantage of 2.5 and where the load lifts by 2.5 metres on pulling the rope by 10 m.
The velocity ratio is the distance moved by the effort divided by the distance moved by the load, that is ten divided by two point five, which is four.
Read the full explanation →The effort applied to move a load is 15 units and the mechanical advantage is observed to be 3. Find the load.
Mechanical advantage is defined as the load divided by the effort, so the load is the mechanical advantage multiplied by the effort, that is three multiplied by fifteen, which gives forty-five units.
Read the full explanation →Consider the following pairs : Region — Country I. Mallorca — Italy II. Normandy — Spain III. Sardinia — France In how many of the above rows is the given information correctly matched?
Mallorca belongs to Spain, Normandy to France and Sardinia to Italy, so every pair in the question is wrong. Mallorca, also spelt Majorca, is the largest of the Balearic Islands in the western Mediterranean and part of Spain; its capital is Palma.
Read the full explanation →Operations undertaken by the Army towards upliftment of the local population in remote areas to include addressing of their basic needs is called :
Sadbhavana, meaning goodwill, is the Indian Army's civic action programme for people in remote and troubled areas. It began in the late 1990s in Jammu and Kashmir and was later taken to Ladakh and the North-East.
Read the full explanation →Consider the following pairs : Country — Resource-rich in I. Botswana — Diamond II. Chile — Lithium III. Indonesia — Nickel In how many of the above rows is the given information correctly matched?
Botswana is rich in diamonds, Chile in lithium and Indonesia in nickel. Botswana is one of the world's leading producers of diamonds by value; the Jwaneng and Orapa mines, run with De Beers, turned it from one of the poorest countries at independence in 1966 into a middle-income one.
Read the full explanation →"Leaf litter decomposes faster than in any other biome and as a result the soil surface is often almost bare. Apart from trees, the vegetation is largely composed of plant forms that reach up into the canopy vicariously, by climbing the trees or growing as epiphytes, rooted on the upper branches of trees." This is the most likely description of
Constant heat and heavy rain make decomposition fastest there, and climbers and epiphytes are its typical plant forms. Tropical rain forests lie near the equator, in the Amazon, the Congo basin and South-East Asia, with temperatures around 27°C and rain in every month.
Read the full explanation →Consider the following statements : 1. In a seismograph, P waves are recorded earlier than S waves. 2. In P waves, the individual particles vibrate to and fro in the direction of wave propagation whereas in S waves, the particles vibrate up and down at right angles to the direction of wave propagation. Which of the statements given above is/are correct?
P waves are the fastest seismic waves and reach a seismograph first, and they move particles along the direction of travel, while S waves move them at right angles to it.
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