NDA 2020 Previous Year GK Questions with Answers

The correct answer is B, Nucleoid. In a prokaryotic cell the genetic material lies free in the cytoplasm with no nuclear membrane around it, and this poorly defined nuclear region is called the nucleoid. Bacteria and blue green algae are prokaryotes, and besides the lack of a true nucleus they have no membrane bound organelles such as mitochondria, plastids or the endoplasmic reticulum; their ribosomes are of the 70S type and their cell wall carries peptidoglycan. Eukaryotes such as fungi, plants and animals keep their DNA inside a double membrane called the nuclear envelope. A is wrong because nucleic acid is the chemical name for DNA and RNA and not a region of the cell. C is wrong because the nucleolus is a dense body inside a true nucleus where ribosomes are put together. D is wrong because a nucleosome is the bead of DNA wound round histone proteins, found in eukaryotes. Exam tip: prokaryote means a nucleoid and no membrane bound organelles.

The correct answer is A, 5, 10 and 2 respectively. Copper sulphate holds five water molecules, sodium carbonate ten and gypsum two, so the order asked for is 5, 10 and 2. Water of crystallisation is the fixed number of water molecules joined to one formula unit of a salt, and it is written after a dot in the formula. Copper sulphate is CuSO4.5H2O, the blue vitriol that turns white on heating and blue again when water is added to it. Sodium carbonate is Na2CO3.10H2O, the washing soda of everyday use, and gypsum is CaSO4.2H2O, which on partial heating gives plaster of Paris. B is wrong because it swaps the figures for copper sulphate and sodium carbonate. C is wrong because it gives sodium carbonate two and gypsum ten. D is wrong because it leaves copper sulphate with only two water molecules. Exam tip: learn the trio together, blue vitriol 5, washing soda 10 and gypsum 2.

The correct answer is D, V D Savarkar. 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. The society trained young men in arms, spread revolutionary literature and had branches in Maharashtra and later in London, where Savarkar went on a scholarship and wrote The Indian War of Independence 1857. It was finally disbanded in 1952. Option A is wrong because Khudiram Bose was a young Anushilan Samiti revolutionary hanged in 1908 for the Muzaffarpur bomb case. Option B is wrong because Shyamji Krishna Verma founded the India House and the Indian Home Rule Society in London in 1905. Option C is wrong because Lala Har Dayal led the Ghadar Party, started in San Francisco in 1913. Exam tip: Abhinav Bharat 1904 Savarkar, India House 1905 Shyamji Krishna Verma, Ghadar Party 1913 Har Dayal.

The correct answer is A, James Chadwick. 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. The only explanation was a particle with no charge and a mass close to that of the proton, which he named the neutron. It completed the picture of the atom, since the nucleus had earlier been short of mass, and it later made nuclear fission possible. Option B is wrong because Rutherford discovered the nucleus through his gold foil experiment and is credited with the proton. Option C is wrong because J. J. Thomson discovered the electron in 1897 with his cathode ray tube. Option D is wrong because John Dalton gave the atomic theory in 1803, long before subatomic particles were known. Exam tip: Thomson for the electron, Rutherford for the proton and nucleus, Chadwick for the neutron.

The correct answer is C, Isaac Newton. Newton passed a narrow beam of sunlight through a glass prism in a darkened room and obtained a band of seven colours on the wall, which he named the spectrum. He then showed with a second prism that the colours could be recombined into white light, proving that the prism does not colour the light but only separates the colours already present in it. The order of the colours from the base of the prism is remembered as VIBGYOR.

Option A, C. V. Raman, discovered the scattering effect named after him and won the Nobel Prize in 1930. Option B, Lord Rayleigh, explained the scattering that makes the sky blue. Option D, S. Chandrasekhar, worked on the structure and evolution of stars.