RRB JE 2019 Previous Year GK Questions with Answers

The correct answer is B, 600 m. The speed of a wave is the product of its frequency and its wavelength, so the speed here is 50 hertz multiplied by 4 metres, that is 200 metres per second. Distance is speed multiplied by time, so in 3 seconds the wave covers 200 multiplied by 3, which is 600 metres. Always find the speed first and only then apply the time.

Option A, 100 m, would follow from dividing rather than multiplying somewhere in the working. Option C, 200 m, is the distance covered in one second and is the answer to a different question; it is the speed, not the answer asked for. Option D, 300 m, corresponds to no correct step at all and is included because it resembles the rounded speed of sound in air, which is irrelevant here since the speed is given indirectly by the data.

The correct answer is B, minus 10 centimetres. By the sign convention the focal length of a concave lens is negative, so f is minus 15 centimetres, and the object distance measured against the direction of the incident light is minus 30 centimetres. Putting these in the lens formula 1/v minus 1/u equals 1/f gives 1/v equal to 1/f plus 1/u, that is minus 1/15 plus minus 1/30, which is minus 3/30 or minus 1/10. Hence v is minus 10 centimetres.

The negative sign shows that the image lies on the same side as the object, so it is virtual and erect, and being nearer the lens than the object it is also diminished. That is true of a concave lens for every position of the object. Options A, C and D come from dropping a sign or from adding the reciprocals wrongly.

The correct answer is Prime Minister's duty regarding keeping the President informed about the government's decisions and policies. Article 78 makes it the duty of the Prime Minister to communicate to the President all decisions of the Council of Ministers relating to the administration of the Union and proposals for legislation; to furnish such information about them as the President may call for; and, if the President so requires, to submit for the Council's consideration any matter on which a minister has decided but which the Council has not considered.

The other options are close enough to confuse. The President's power to send messages to Parliament is in Article 86. Emergency powers are in Part XVIII, Articles 352 to 360. Option C describes the effect of Article 78 from the President's side, but the Article is framed as a duty of the Prime Minister, which is what the question asks. Article 78 is what makes the Prime Minister the link between the President and the Council of Ministers.

The correct answer is B, Rajasthan. Ghoomar is a folk dance of Rajasthan performed by women in long, flared skirts called ghaghras, who spin gracefully in circles. The name comes from 'ghoomna', meaning to twirl, and the swirling of the ghaghra is the heart of the dance. It was first developed by the Bhil tribe and later adopted by the Rajput royal families, and today it is danced at weddings and at festivals such as Teej and Gangaur. Rajasthan's other famous folk dances include Kalbeliya, the dance of the snake-charmer community that is on UNESCO's intangible heritage list, Chari, Kachchhi Ghodi and Terah Taali. A is wrong because Gujarat's best-known folk dances are Garba and Dandiya Raas. C is wrong because Kerala is known for Kathakali, Mohiniyattam and the ritual art of Theyyam. D is wrong because Sikkim is known for dances such as Singhi Chham, the snow lion dance. Exam tip: Ghoomar and Kalbeliya = Rajasthan; Garba and Dandiya = Gujarat.

The correct answer is B, Quit India Movement. Mahatma Gandhi gave the call 'Do or Die' (Karo ya Maro) when the Quit India Movement was launched in August 1942. The Congress passed the Quit India resolution at its Bombay session on 8 August 1942, and in his speech at Gowalia Tank Maidan, now August Kranti Maidan, Gandhi told Indians to win freedom or die trying. The British arrested Gandhi, Nehru and other leaders early the next morning, and Aruna Asaf Ali hoisted the Congress flag at the same ground. With the leaders in jail, the movement was carried on by students, workers and underground leaders such as Jayaprakash Narayan and Ram Manohar Lohia. A is wrong because the Swadeshi Movement began in 1905 against the partition of Bengal. C is wrong because the Civil Disobedience Movement began with the Dandi March in 1930. D is wrong because the Non-Cooperation Movement ran from 1920 to 1922. Exam tip: 1942 = Quit India = 'Do or Die'; 9 August is marked as August Kranti Day.

The correct answer is A, Madhya Pradesh. Kanha Tiger Reserve lies in the Mandla and Balaghat districts of Madhya Pradesh, in the Maikal hills at the eastern end of the Satpura range. It was among the first nine tiger reserves created when Project Tiger was launched in 1973. Kanha is best known for saving the hard-ground barasingha, a swamp deer that had almost died out and is now the state animal of Madhya Pradesh. Its open sal forests and grassy meadows make it one of the best places in India to see tigers in the wild. Madhya Pradesh's other well-known tiger reserves include Bandhavgarh, Panna, Pench and Satpura. B is wrong because Karnataka's famous tiger reserves are Bandipur and Nagarhole. C is wrong because Odisha's main tiger reserve is Similipal. D is wrong because Maharashtra's best-known tiger reserves are Tadoba-Andhari and Melghat. Exam tip: Kanha = Madhya Pradesh = barasingha; one of the first nine Project Tiger reserves of 1973.

The correct answer is C, Polythene bag. Polythene is a synthetic plastic that bacteria and fungi cannot break down, so it is non-biodegradable. A plastic bag can stay in soil or water for hundreds of years. Biodegradable waste is anything that decomposers can break down into simple, harmless substances, and it usually comes from plants or animals. Plastic bags choke drains and cause waterlogging, are swallowed by cattle and sea animals, and give off toxic gases when burnt, which is why their use must be reduced and the bags reused and recycled rather than thrown away. Waste is best kept in two bins: wet (biodegradable) and dry (non-biodegradable). A is wrong because vegetable peels rot within days and make good compost. B is wrong because dead leaves decay into humus that enriches the soil. D is wrong because a rotting fruit is already being broken down by microbes. Exam tip: if microbes can eat it, it is biodegradable; plastic, glass, metal cans and DDT are not.

The correct answer is D, 32. The N shell is the fourth shell (n = 4), and the most electrons a shell can hold is given by the formula 2n², so 2 × 4² = 32. The shells around the nucleus are named K, L, M and N for n = 1, 2, 3 and 4, and the same formula gives them room for 2, 8, 18 and 32 electrons. This is the Bohr–Bury scheme taught in Class 9. One more rule is often tested with it: the outermost shell of an atom cannot hold more than 8 electrons, which is why potassium is written 2, 8, 8, 1 and not 2, 8, 9. A is wrong because 2 is the capacity of the K shell. B is wrong because 8 is the capacity of the L shell. C is wrong because 16 is not the capacity of any shell; the M shell holds 18. Exam tip: remember 2n², so K = 2, L = 8, M = 18 and N = 32.

The correct answer is D, Four. In diamond every carbon atom is joined to four other carbon atoms by strong covalent bonds. These bonds point towards the corners of a tetrahedron and build a rigid three-dimensional network that runs through the whole crystal. That network makes diamond the hardest natural substance, which is why it is used in cutting and drilling tools. Since all four valence electrons are used in bonding, no free electrons are left, so diamond does not conduct electricity. In graphite, the other common form of carbon, each atom bonds to only three others in flat hexagonal layers, and the spare electron lets graphite conduct. A is wrong because two bonds per carbon cannot build a solid network. B is wrong because carbon has a valency of four and cannot form five bonds. C is wrong because three bonds per atom describes graphite, not diamond. Exam tip: diamond = 4 bonds, hard, insulator; graphite = 3 bonds, soft, conductor.

The correct answer is D, New Cartesian sign convention. It is the standard set of rules used for reflection by spherical mirrors and for the mirror formula. Under this convention the pole of the mirror is the origin and the principal axis is the x-axis. The object is always placed on the left, all distances are measured from the pole, distances in the direction of the incident light are positive and those against it are negative. Heights above the axis are positive and below it negative, so a concave mirror has a negative focal length and a convex mirror a positive one. A is wrong because 'system convention' is not a named rule in optics. B is wrong because 'sign convention' is only the general idea; the specific set used is the New Cartesian one. C is wrong because 'mirror convention' is not a recognised term. Exam tip: New Cartesian means measure from the pole; concave f is negative, convex f is positive; mirror formula 1/v + 1/u = 1/f.