Railway Previous Year GK Questions with Answers

The correct answer is C, 240 J. Work done against gravity is weight multiplied by height, so 120 × 2 = 240 joules. Work is done when a force moves a body along the direction of that force, and it is measured as W = F × s. Here the boy must at least match the weight of the box, which is 120 N, and he moves it through 2 m, so the work done is 240 J. This work is stored in the box as gravitational potential energy, and the box would give back the same 240 J if it fell to where it started. Note that the weight is already given in newtons, so there is no need to multiply by g again. Option A is wrong because 60 J divides the weight by the height instead of multiplying. Option B is wrong because 120 J is only the weight in newtons, with the height left out. Option D is wrong because 130 J matches no step of the calculation. Exam tip: W = F × s, and work done against gravity is mgh, where mg is the weight.

The correct answer is B, Friction. Brakes work on friction: a lining is pressed against a moving drum or disc, and the rubbing force slows the wheel down. Friction is the force that opposes motion between two surfaces in contact. In a drum brake the shoes push outward against the inner face of the drum, while in a disc brake the pads grip a rotating disc from both sides; in each case the kinetic energy of the vehicle is turned into heat, which is why brakes grow hot on a long downhill run. The friction between the tyre and the road then stops the vehicle itself, so a smooth or wet road lengthens the stopping distance. Option A is wrong because vibration only shakes a body and cannot take away its energy in a controlled way. Option C is wrong because suction is a pressure difference; a vacuum booster only helps the driver press the pedal, it does not stop the wheel. Option D is wrong because dragging is not a physical principle. Exam tip: brakes turn kinetic energy into heat through friction.

The correct answer is A, 6.67 m/s². Find each mass from F = ma, add the masses, then divide the same force by the total. The first block gives m1 = 5 ÷ 10 = 0.5 kg and the second gives m2 = 5 ÷ 20 = 0.25 kg. Tied together they move as one body of mass 0.5 + 0.25 = 0.75 kg, and the same 5 N force now produces an acceleration of 5 ÷ 0.75, which is about 6.67 m/s². The joint acceleration is always less than the smaller of the two single accelerations, because the same push has to move more mass. Option B is wrong because 1.67 m/s² matches no step of this working. Option C is wrong because 5.67 m/s² would need a total mass of about 0.88 kg. Option D is wrong because 4.67 m/s² would need a total mass of about 1.07 kg. Exam tip: for one force on tied blocks the reciprocals add, that is 1 by a equals 1 by a1 plus 1 by a2.

The correct answer is A, 275 J. Kinetic energy is half m v squared, so half of 22 multiplied by 5 multiplied by 5 gives 275 joules. Kinetic energy is the energy a body has because of its motion. It rises in direct proportion to the mass but with the square of the speed, so doubling the speed makes the energy four times larger, which is why a fast vehicle needs a much longer distance to stop than a slow one. The joule is the SI unit of energy and equals one newton metre; one joule is the work done when a force of one newton moves a body through one metre. Option B is wrong because 110 J is mass multiplied by speed, which gives momentum, not energy, and in different units. Option C is wrong because 1100 J leaves out the half in the formula, that is it works out m v squared. Option D is wrong because 2750 J is ten times the correct value. Exam tip: write half m v squared carefully, because the half and the squared speed are where marks are usually lost.

The correct answer is B, 0 J. The body is thrown up at 20 m/s and gravity takes away 10 m/s of speed every second, so after 2 seconds its speed is zero. Using v = u − gt, we get v = 20 − 10 × 2 = 0 m/s. Kinetic energy is half m v squared, and with v = 0 the kinetic energy is also zero. At that instant the body is at the highest point of its path and all of its energy is potential energy, mgh = 2 × 10 × 20 = 400 J, since the body has risen 20 m. A moment later it begins to fall and the kinetic energy grows again. Option A is wrong because 100 J needs a speed of 10 m/s, which the body has after only one second. Option C is wrong because 400 J is the kinetic energy at the moment of throwing, and the potential energy at the top. Option D is wrong because 200 J matches no point of this motion. Exam tip: at the highest point of a vertical throw the speed, and so the kinetic energy, is zero.

The correct answer is C, Boron. Boron has three electrons in its outermost shell, so it is a trivalent element and is used as a p-type dopant. When a trivalent atom such as boron, aluminium, gallium or indium is added to silicon or germanium, it can form only three covalent bonds with its four neighbours, so one bond is left incomplete. That empty place is called a hole, it behaves like a positive charge carrier, and the doped crystal becomes a p-type semiconductor in which holes are the majority carriers. Adding a pentavalent atom instead leaves a free electron and gives an n-type semiconductor. Option A is wrong because arsenic has five valence electrons and is pentavalent. Option B is wrong because antimony is also pentavalent and is used for n-type doping. Option D is wrong because phosphorus has five valence electrons and donates an electron to the crystal. Exam tip: trivalent dopants such as boron, aluminium, gallium and indium give p-type material, while pentavalent ones such as phosphorus, arsenic and antimony give n-type.

The correct answer is C, Anti-lock braking system. ABS stands for anti-lock braking system, a safety device that keeps the wheels from locking during hard braking. Sensors at the wheels watch how fast each one is turning, and when a wheel is about to stop turning the control unit releases and applies the brake pressure many times a second. Because the wheels keep rolling, the tyres hold their grip on the road, so the driver can still steer while braking hard and the vehicle usually stops in a shorter distance. A locked wheel simply skids and goes wherever it was already going. ABS is now required by law on cars and on larger two-wheelers in India. Option A is wrong because 'avoid brake system' is not a term used for any vehicle part. Option B is wrong because 'actual brake system' has no meaning in engineering. Option D is wrong because an automatic braking system is a different feature in which the vehicle applies the brakes by itself to avoid a crash. Exam tip: ABS prevents wheel lock and keeps steering control; it does not replace the brakes.

The correct answer is A, 2. A centre-tap full wave rectifier needs two p-n junction diodes, one for each half of the input cycle. The secondary winding of the transformer is tapped at its middle, so its two halves give equal voltages of opposite sign. During one half cycle the upper diode conducts and during the next half cycle the lower diode conducts, and both send current through the load in the same direction, so the output has two pulses in every cycle. That is why a full wave rectifier gives a higher average output and a lower ripple than a half wave one. The other way to build a full wave rectifier is the bridge circuit, which uses four diodes but needs no centre tap. Option B is wrong because one diode makes a half wave rectifier that uses only half of each cycle. Option C is wrong because four diodes are used in a bridge rectifier. Option D is wrong because six diodes are used in a three-phase full wave rectifier. Exam tip: half wave 1 diode, centre-tap full wave 2, bridge 4.

The correct answer is A, Liquid. At normal atmospheric pressure water stays liquid between 0 °C and 100 °C, and 12 °C lies inside that range. Water freezes into ice at 0 °C, which is its melting point, and boils into steam at 100 °C, which is its boiling point, when the pressure is one atmosphere. Between these two fixed points the molecules have enough energy to slide over one another but not enough to fly apart, so water flows and takes the shape of its container while keeping a fixed volume. Water does evaporate slowly at 12 °C from an open surface, but that happens only at the top layer and does not change the state of the water below. Option B is wrong because ionic is not a state of matter at all; it describes a kind of bond or compound. Option C is wrong because water becomes a gas, that is steam, only above 100 °C. Option D is wrong because water turns solid only at or below 0 °C. Exam tip: remember 0 °C and 100 °C as the fixed points of water at one atmosphere.

The correct answer is C, 16 times the initial value. Kinetic energy depends on the square of the momentum, so the momentum grows as the square root of the energy. For a body of mass m, the kinetic energy can be written as p squared divided by 2m, where p is the linear momentum. If the mass does not change, p equals the square root of 2mE, so p is proportional to the square root of E. When the kinetic energy becomes 256 times, the momentum becomes the square root of 256, that is 16 times its earlier value, and the speed also becomes 16 times. Option A is wrong because a body cannot gain energy while its momentum stays the same. Option B is wrong because 8 times the momentum would make the energy 64 times, not 256 times. Option D is wrong because 32 times the momentum would make the energy 1024 times. Exam tip: E equals p squared by 2m, so if the energy becomes n times the momentum becomes root n times, and if the momentum becomes n times the energy becomes n squared times.

The correct answer is D, 0.7 V. A silicon diode in forward bias drops about 0.7 volt across itself, whatever the supply voltage is. This value is the barrier or knee voltage of a silicon p-n junction: current begins to flow only after the applied voltage crosses about 0.7 V, and after that the drop across the diode stays near 0.7 V while the rest of the supply appears across the resistor. Here 12 V minus 0.7 V, that is 11.3 V, falls across the 240 ohm resistor and fixes the current in the circuit. A germanium diode has a lower knee voltage of about 0.3 V. Option A is wrong because 1.5 V is the voltage of a dry cell and has nothing to do with the junction. Option B is wrong because half the supply would appear across the diode only if it behaved like a resistor of the same value. Option C is wrong because the full 12 V appears across the diode only when it is reverse biased or the circuit is broken. Exam tip: silicon 0.7 V, germanium 0.3 V.

The correct answer is B, The stamen and pistil. The stamen and the pistil make the male and female gametes, so they are the essential or reproductive organs of a flower. The stamen is the male part and has an anther that produces pollen grains and a filament that holds the anther up. The pistil, also called the carpel, is the female part and has three portions: the stigma that receives the pollen, the style, and the ovary that holds the ovules. After pollination and fertilisation the ovary grows into the fruit and the ovules become seeds. Sepals and petals are called accessory organs because they only protect the bud and attract insects for pollination. Option A is wrong because the sepal is only the green leaf-like part that covers the bud. Option C is wrong because neither sepals nor petals take any part in making gametes. Option D is wrong because the petal is accessory, even though the pistil named with it is essential. Exam tip: stamen and pistil are essential, sepal and petal are accessory.

The correct answer is C, Silver. Silver is a noble metal and does not combine with oxygen even when it is heated strongly. Metals react with oxygen according to their place in the reactivity series. Very reactive metals such as potassium and sodium burn in air at room temperature, aluminium and zinc form an oxide layer when heated, and lead slowly turns into lead oxide on heating. Silver, gold and platinum lie at the bottom of the series, so they keep their shine in air; the black film that appears on silverware is silver sulphide formed by sulphur gases, not silver oxide. Option A is wrong because zinc burns with a bluish white flame and gives zinc oxide. Option B is wrong because aluminium forms a thin, tough coat of aluminium oxide that protects the metal below it. Option D is wrong because lead heated in air gives litharge, which is lead oxide. Exam tip: gold, silver and platinum are the noble metals that resist oxidation, which is why they are used in jewellery and contacts.

The correct answer is B, Cambodia. Angkor Wat stands near Siem Reap in Cambodia and is the largest religious monument in the world. It was built in the early twelfth century by King Suryavarman II of the Khmer empire as a temple of Vishnu, and it later became a Buddhist place of worship. The temple faces west, is ringed by a wide moat, and its towers are shaped like lotus buds; UNESCO put the whole Angkor complex on the World Heritage list in 1992. Angkor Wat also appears on the national flag of Cambodia, which is the only national flag in the world that carries a building. Option A is wrong because Vietnam is known for Ha Long Bay and the My Son Cham temples. Option C is wrong because Thailand's best known temple is Wat Phra Kaew in Bangkok. Option D is wrong because the Philippines is known for its rice terraces and baroque churches. Exam tip: Angkor Wat, Cambodia, built by Suryavarman II and shown on that country's flag.

The correct answer is D, 75%. The ball falls from 10 m but rises back only 2.5 m, so it keeps one quarter of its energy and loses three quarters. Just before the ball hits the ground, its kinetic energy equals the potential energy it had at the top, that is mgh with h = 10 m. Just after the bounce, the kinetic energy is only as much as is needed to lift it 2.5 m, so it is mg multiplied by 2.5. The ratio is 2.5 divided by 10, which is one fourth, so 25 per cent of the kinetic energy is left and 75 per cent is lost as heat and sound during the collision. The mass cancels out, so the heights alone decide the answer. Option A is wrong because the ball does rebound, so all the energy is not lost. Option B is wrong because 25 per cent is the energy kept, not the energy lost. Option C is wrong because losing half the energy would take the ball back to 5 m. Exam tip: in a bounce, percentage loss equals (1 minus h2 by h1) multiplied by 100.

The correct answer is D, Mamta Kalia. The Vyas Samman for 2017 went to the Hindi writer Mamta Kalia for her novel 'Dukham Sukham'. The Vyas Samman is given every year by the K.K. Birla Foundation for an outstanding Hindi work published in the previous ten years, and it carries a citation and a cash prize. The same foundation gives two other literary awards: the Saraswati Samman, open to a work in any language listed in the Eighth Schedule, and the Bihari Puraskar for writing from Rajasthan. Mamta Kalia is known for her Hindi stories and novels and has headed the Mahadevi Verma Srijan Peeth in Allahabad. Option A is wrong because Namita Gokhale writes in English and co-founded the Jaipur Literature Festival. Option B is wrong because Meena Kandasamy is an English-language poet and translator. Option C is wrong because Jhumpa Lahiri writes in English and won the Pulitzer Prize for 'Interpreter of Maladies'. Exam tip: Vyas Samman is for Hindi alone, while Saraswati Samman covers all Eighth Schedule languages.

The correct answer is C, spam. Unwanted bulk messages sent to many people to advertise something are called spam. Spam usually arrives as e-mail, but the same word is used for unwanted SMS, blog comments and social media messages. Mail services run spam filters that study the sender, the subject line and the words used, and move such mail to a separate Spam or Junk folder so that it never reaches the inbox. Spam that pretends to come from a bank and asks for passwords or card details is called phishing, and a person who sends spam is a spammer. Option A is wrong because a virus is a harmful program that copies itself into other files and damages data. Option B is wrong because unzip only means opening a compressed file such as a .zip archive. Option D is wrong because a URL is the address of a web page. Exam tip: unwanted bulk mail is spam, while fake mail that asks for your details is phishing.

The correct answer is A, 1969. On 19 July 1969 the Government of India issued an ordinance taking over the fourteen largest Indian scheduled commercial banks, those whose deposits stood at ₹50 crore or more. Indira Gandhi held the Finance portfolio along with the Prime Minister's office at the time, and the stated purpose was to direct credit to agriculture, small industry and the unbanked districts.

Option B, 1970, is the year the Banking Companies (Acquisition and Transfer of Undertakings) Act was passed to replace the ordinance after the Supreme Court struck it down, which is why the year is a favourite distractor. Option C, 1972, belongs to no step in the nationalisation story. Option D, 1950, is far too early; in that year the Reserve Bank had been in public ownership for barely a year and commercial banking was still entirely private. The second round of nationalisation, of six banks, came on 15 April 1980.

The correct answer is The Vice President. Article 64 makes the Vice-President the ex officio Chairman of the Council of States, that is, the Rajya Sabha. "Ex officio" means by virtue of the office: nobody elects the Chairman separately. The Vice-President is not a member of the Rajya Sabha and so cannot vote in the first instance, but has a casting vote to break a tie. The Rajya Sabha elects a Deputy Chairman from among its members to preside in the Chairman's absence.

The Governor heads a State and has no role in Parliament. The President is part of Parliament under Article 79 and addresses it, but does not preside over either House. The Prime Minister leads the government and, as a member of one House, is the Leader of that House, but never its presiding officer. Note that when the Vice-President acts as President, he or she does not perform the duties of Chairman of the Rajya Sabha during that period.

The correct answer is President. Article 123 lets the President promulgate an ordinance when either House of Parliament is not in session and the President is satisfied that circumstances make immediate action necessary. An ordinance has the same force as an Act of Parliament, but it must be laid before both Houses when they reassemble and lapses six weeks after that unless approved earlier. It can be withdrawn at any time, and it cannot amend the Constitution.

The Vice-President has no power to make laws; the Prime Minister and the Council of Ministers advise the President to issue an ordinance but cannot issue one themselves; and the Speaker of the Lok Sabha presides over the House but has no ordinance-making power. The State counterpart is the Governor's power under Article 213. Remember too that the maximum life of an ordinance is six months and six weeks, because Parliament must meet at least once every six months.