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Railway Previous Year GK Questions with Answers

General knowledge questions asked in the official papers of Railway exams, RRB NTPC, RRB Group D, RRB ALP and RRB JE, in one place. Each comes with the correct answer, an explanation and the exam, year and shift it was asked in.

Pick a year below to see that year's questions, or open an exam's own page for its papers alone. Questions from one exam are often asked again in another, so revising the whole Railway family together is a quick way to cover what the papers test.

Previous Year Questions

Q141.Static GKAsked in: RRB Group D · 5 Oct 2018, Shift 2Easy

Where is Angel Falls located?

  1. A.Venezuela
  2. B.Brazil
  3. C.United States of America
  4. D.China
Show answer

Correct answer: A. Venezuela

Explanation

The correct answer is A, Venezuela. Angel Falls, in the Canaima National Park of Venezuela, is the highest uninterrupted waterfall in the world, with a total height of about 979 metres and a single unbroken drop of about 807 metres. It pours off the edge of Auyan-tepui, a flat-topped table mountain, and the local Pemon people call it Kerepakupai Meru. It is named after Jimmie Angel, an American pilot who flew over it in 1933. The falls are so remote that most visitors reach them by small plane and then by boat along jungle rivers. B is wrong because Brazil shares the wide Iguazu Falls with Argentina, which are famous for their width, not height. C is wrong because the USA shares Niagara Falls with Canada, which are wide but only about 50 metres high. D is wrong because China is known for the Huangguoshu Falls, which are far lower. Exam tip: highest waterfall = Angel Falls (Venezuela); Iguazu = Brazil and Argentina; Victoria Falls = Zambia and Zimbabwe; Niagara = USA and Canada.

Q142.Static GKAsked in: RRB Group D · 17 Dec 2018, Shift 2Easy

Which Indian city is known as 'The City of Palaces'?

  1. A.Kolkata
  2. B.Hyderabad
  3. C.Mumbai
  4. D.Chennai
Show answer

Correct answer: A. Kolkata

Explanation

The correct answer is A, Kolkata. Kolkata earned the name City of Palaces in the colonial era for the grand mansions built by British officials and rich Bengali families along its main streets. It was the capital of British India until 1911, when the capital moved to Delhi, and many of those buildings still stand, from the Victoria Memorial to the Marble Palace and the Writers Building. The city also carries the names City of Joy and the cultural capital of India, and it was the first city in India to get a metro railway, in 1984. B is wrong because Hyderabad is the City of Pearls and the City of Nizams. C is wrong because Mumbai is known as the Gateway of India, the City of Seven Islands and the financial capital of India. D is wrong because Chennai is called the Gateway of South India and the Detroit of India for its car industry. Exam tip: Kolkata = City of Palaces and City of Joy; Hyderabad = City of Pearls; Jaipur = Pink City; Udaipur = City of Lakes.

Q143.Static GKAsked in: RRB Group D · 29 Aug 2022, Shift 2Easy

In which of the following cities is the Headquarters of the Ministry of Panchayati Raj located?

  1. A.Jaipur
  2. B.New Delhi
  3. C.Chennai
  4. D.Pune
Show answer

Correct answer: B. New Delhi

Explanation

The correct answer is B, New Delhi. The Ministry of Panchayati Raj is a Union ministry, and like every ministry of the Government of India it works from the national capital, New Delhi. It was set up as a separate ministry in May 2004 to look after the three-tier system of village, block and district panchayats. That system got constitutional status through the 73rd Amendment Act, 1992, which came into force on 24 April 1993; this is why 24 April is observed as National Panchayati Raj Day. Part IX of the Constitution and the Eleventh Schedule, with 29 subjects, deal with panchayats. A is wrong because Jaipur is the capital of Rajasthan; Rajasthan was the first state to start Panchayati Raj, at Nagaur on 2 October 1959, but the ministry is not there. C is wrong because Chennai is the capital of Tamil Nadu. D is wrong because Pune is a city of Maharashtra, not a seat of Union ministries. Exam tip: Union ministries = New Delhi; 73rd Amendment = panchayats; first Panchayati Raj = Nagaur, Rajasthan, 2 October 1959.

Q144.Indian EconomyAsked in: RRB Group D · 29 Oct 2018, Shift 3Medium

RBI was nationalized in ________.

  1. A.1949
  2. B.1962
  3. C.1947
  4. D.1955
Show answer

Correct answer: A. 1949

Explanation

The correct answer is A, 1949. The Reserve Bank of India was nationalised on 1 January 1949 under the Reserve Bank of India (Transfer to Public Ownership) Act, 1948. Until then it was owned by private shareholders. The RBI was set up on 1 April 1935 under the Reserve Bank of India Act, 1934, on the recommendation of the Hilton Young Commission. Its first office was in Calcutta and it moved permanently to Bombay, now Mumbai, in 1937. C.D. Deshmukh, appointed in 1943, was its first Indian Governor. B is wrong because 1962 is not linked to the RBI's ownership. C is wrong because 1947 was the year of Independence; the RBI still had private shareholders then. D is wrong because 1955 is when the Imperial Bank of India became the State Bank of India. Exam tip: RBI set up 1 April 1935, nationalised 1 January 1949; SBI formed 1955; 14 major banks nationalised in 1969.

Q145.Indian EconomyAsked in: RRB Group D · 26 Aug 2022, Shift 3Medium

Who was the first Deputy Chairman of the Planning Commission of India?

  1. A.Vallabhbhai Jhaverbhai Patel
  2. B.Gulzarilal Nanda
  3. C.KC Neogy
  4. D.Jawaharlal Nehru
Show answer

Correct answer: B. Gulzarilal Nanda

Explanation

The correct answer is B, Gulzarilal Nanda. Gulzarilal Nanda became the first Deputy Chairman when the Planning Commission began work in 1950, and he later became interim Prime Minister twice, in 1964 and 1966. The Planning Commission was set up by a Cabinet resolution on 15 March 1950 with the Prime Minister as its ex-officio Chairman; it was neither a constitutional nor a statutory body. Nanda was also Union Planning Minister and received the Bharat Ratna in 1997. The Commission was replaced by NITI Aayog on 1 January 2015. A is wrong because Sardar Patel was Deputy Prime Minister and Home Minister and never served on the Planning Commission. C is wrong because K.C. Neogy headed the first Finance Commission in 1951. D is wrong because Nehru was the Chairman of the Planning Commission as Prime Minister, not its Deputy Chairman. Exam tip: Planning Commission 1950, Chairman = Prime Minister, first Deputy Chairman = Gulzarilal Nanda; NITI Aayog replaced it on 1 January 2015.

Q146.Indian EconomyAsked in: RRB Group D · 22 Aug 2022, Shift 1Medium

The Regional Rural Banks Act was passed in which year by the Government of India?

  1. A.1966
  2. B.1976
  3. C.1986
  4. D.1996
Show answer

Correct answer: B. 1976

Explanation

The correct answer is B, 1976. Regional Rural Banks were set up under the Regional Rural Banks Act, 1976, after the Narasimham Working Group of 1975 recommended small banks close to the villages. The first RRB, Prathama Bank, opened at Moradabad in Uttar Pradesh on 2 October 1975 under an ordinance, and the Act followed in 1976. Each RRB is sponsored by a commercial bank, and its capital is shared by the Centre (50 per cent), the sponsor bank (35 per cent) and the State government (15 per cent). Their aim is credit for small farmers, artisans and rural labourers, and NABARD supervises them. A is wrong because in 1966 rural credit still depended on cooperatives; no RRB law existed. C is wrong because 1986 saw no such Act. D is wrong because 1996 is long after the Act, not the year it was passed. Exam tip: RRB Act 1976; first RRB Prathama Bank, 2 October 1975; capital shared 50:35:15 between Centre, sponsor bank and State.

Q147.GeographyAsked in: RRB Group D · 23 Sep 2018, Shift 1Medium

The Rana Pratap Sagar Dam is built on the river __________.

  1. A.Ganga
  2. B.Jhelum
  3. C.Beas
  4. D.Chambal
Show answer

Correct answer: D. Chambal

Explanation

The correct answer is D, Chambal. Rana Pratap Sagar Dam stands on the Chambal at Rawatbhata in the Chittorgarh district of Rajasthan. It is one of the four structures of the Chambal Valley Project: Gandhi Sagar Dam upstream in Madhya Pradesh, then Rana Pratap Sagar, Jawahar Sagar and the Kota Barrage in Rajasthan. The dam was completed in 1970 and has a hydropower station of 172 MW, and the Rajasthan Atomic Power Station also stands at Rawatbhata. The Chambal rises in the Janapav hills near Mhow in Madhya Pradesh and joins the Yamuna in Uttar Pradesh. A is wrong because the Ganga is known for the Farakka Barrage, not this dam. B is wrong because the Jhelum carries projects such as Uri in Jammu and Kashmir. C is wrong, and is the usual trap, because the Pong Dam on the Beas in Himachal Pradesh has a reservoir called Maharana Pratap Sagar. Exam tip: Rana Pratap Sagar = Chambal (Rajasthan); Maharana Pratap Sagar = Pong Dam on the Beas.

Q148.GeographyAsked in: RRB Group D · 29 Oct 2018, Shift 2Easy

Shillong is the capital of ________.

  1. A.Tripura
  2. B.Meghalaya
  3. C.Nagaland
  4. D.Assam
Show answer

Correct answer: B. Meghalaya

Explanation

The correct answer is B, Meghalaya. Shillong is the capital of Meghalaya, the hill state whose name means abode of the clouds. Meghalaya was carved out of Assam and became a full state on 21 January 1972, the same day as Manipur and Tripura. Before that, Shillong had been the capital of undivided Assam, and its pine hills and cool weather earned it the name Scotland of the East. The state is home to the Khasi, Garo and Jaintia hills, and Mawsynram and Cherrapunji (Sohra) in the Khasi hills are among the wettest places on Earth. A is wrong because the capital of Tripura is Agartala. C is wrong because the capital of Nagaland is Kohima. D is wrong because Assam moved its capital from Shillong to Dispur, in Guwahati, after Meghalaya was formed. Exam tip: Shillong = Meghalaya, Kohima = Nagaland, Agartala = Tripura, Dispur = Assam, Imphal = Manipur, Aizawl = Mizoram, Itanagar = Arunachal Pradesh.

Q149.GeographyAsked in: RRB Group D · 29 Sep 2022, Shift 2Hard

Which of the following statements is INCORRECT about soil formation?

  1. A.Temperature and rainfall influence rate of weathering.
  2. B.Time determines thickness of soil profile.
  3. C.Parent rock determines colour.
  4. D.Altitude and slope determine the rate of humus formation.
Show answer

Correct answer: D. Altitude and slope determine the rate of humus formation.

Explanation

The correct answer is D, Altitude and slope determine the rate of humus formation. Altitude and slope, which together make up relief, decide how much soil collects at a place, not how fast humus forms. Humus is the dark organic matter made when dead leaves and animals rot, and its rate of formation depends on climate and on the living things in the soil: plants, animals and micro-organisms. NCERT lists five factors of soil formation. Parent rock gives the soil its colour, texture and minerals; climate, meaning temperature and rainfall, sets the rate of weathering and humus formation; relief, meaning altitude and slope, controls how much soil accumulates; time decides the thickness of the soil profile; and flora, fauna and microbes affect humus. A is wrong as a choice because temperature and rainfall really do control weathering. B is wrong because time does decide how thick the profile grows. C is wrong because parent rock does fix the colour of soil. Exam tip: relief = accumulation of soil; climate and organisms = humus; parent rock = colour and texture; time = thickness.

Q150.GeographyAsked in: RRB Group D · 1 Oct 2018, Shift 2Easy

Nainital lake is situated in the state of __________.

  1. A.Assam
  2. B.Himachal Pradesh
  3. C.Uttarakhand
  4. D.Uttar Pradesh
Show answer

Correct answer: C. Uttarakhand

Explanation

The correct answer is C, Uttarakhand. Nainital, the eye-shaped lake, lies in the Kumaon hills of Uttarakhand at a height of about 1,938 metres. The town grew around it after the British trader P. Barron reached the lake in 1841, and it became the summer capital of the United Provinces. The lake is a natural crescent, with Mallital at its northern end and Tallital at its southern end, and the Naina Devi temple on its bank gives it its name. Nearby lakes of the same district are Bhimtal, Sattal and Naukuchiatal, which is why the area is called the Lake District of India. A is wrong because Assam's well-known lakes are Chandubi and Deepor Beel. B is wrong because Himachal Pradesh has Renuka, Rewalsar and Chandra Tal. D is wrong because Nainital was part of Uttar Pradesh only until Uttarakhand was carved out in November 2000. Exam tip: Nainital, Bhimtal, Sattal and Naukuchiatal all lie in the Kumaon region of Uttarakhand.

Q151.Indian HistoryAsked in: RRB Group D · 9 Oct 2018, Shift 3Easy

Amir Khusro was a famous musician in the court of which emperor?

  1. A.Shahjahan
  2. B.Aurangzeb
  3. C.Jahangir
  4. D.Alauddin Khilji
Show answer

Correct answer: D. Alauddin Khilji

Explanation

The correct answer is D, Alauddin Khilji. Amir Khusro was the court poet and musician of Alauddin Khalji, and he lived in the courts of several Delhi sultans from Balban's time to Ghiyasuddin Tughlaq. He was a disciple of the Sufi saint Nizamuddin Auliya and is buried near his dargah in Delhi. He wrote in Persian and in Hindavi, the early form of Hindi and Urdu, and is called Tuti-e-Hind, the Parrot of India. Tradition credits him with the qawwali and with ragas and forms such as tarana, and his Khazain-ul-Futuh describes Alauddin's campaigns. Popular belief also links him to the sitar and the tabla, though historians doubt this. A is wrong because Shah Jahan was a Mughal emperor who ruled about three centuries later. B is wrong because Aurangzeb, also a Mughal, banned music at his court. C is wrong because Jahangir was a Mughal emperor known for his love of painting. Exam tip: Amir Khusro = Alauddin Khalji's court, disciple of Nizamuddin Auliya, Parrot of India, father of qawwali.

Q152.Indian HistoryAsked in: RRB Group D · 11 Dec 2018, Shift 2Easy

The period between _____ is known as the period of Delhi Sultanate.

  1. A.1106 AD and 1326 AD
  2. B.1606 AD and 1826 AD
  3. C.1206 AD and 1526 AD
  4. D.1006 AD and 1326 AD
Show answer

Correct answer: C. 1206 AD and 1526 AD

Explanation

The correct answer is C, 1206 AD and 1526 AD. The Delhi Sultanate began in 1206, when Qutb-ud-din Aibak became the first sultan after the death of Muhammad Ghori, and ended in 1526, when Babur defeated Ibrahim Lodi at the First Battle of Panipat. In these 320 years five dynasties ruled from Delhi in this order: the Mamluk or Slave dynasty, the Khalji, the Tughlaq, the Sayyid and the Lodi. The Tughlaqs ruled the longest and the Khaljis the shortest. Famous rulers of the period include Iltutmish, Razia Sultan, the first woman to rule from Delhi, Balban, Alauddin Khalji and Muhammad bin Tughlaq. A is wrong because 1106 is a century before the Sultanate began. B is wrong because 1606 to 1826 falls in the Mughal and British periods. D is wrong because 1006 is the time of the raids of Mahmud of Ghazni, and 1326 falls in the middle of Tughlaq rule. Exam tip: Delhi Sultanate = 1206 to 1526; dynasty order Slave, Khalji, Tughlaq, Sayyid, Lodi.

Q153.Indian HistoryAsked in: RRB Group D · 22 Sep 2018, Shift 2Easy

Hamida Banu Begum was the mother of ________.

  1. A.Emperor Humayun
  2. B.Emperor Jahangir
  3. C.Emperor Akbar
  4. D.Emperor Babur
Show answer

Correct answer: C. Emperor Akbar

Explanation

The correct answer is C, Emperor Akbar. Hamida Banu Begum was the wife of Humayun and the mother of Akbar, who was born to her in 1542 at Amarkot in Sindh. Humayun married her in 1541 while he was on the run after losing his throne to Sher Shah Suri at the battles of Chausa (1539) and Kannauj (1540). Akbar was born during these years of exile, and Humayun won back Delhi only in 1555, a few months before his death. Hamida Banu was honoured with the title Maryam Makani, and she lived on at the court of her son until her death in 1604. A is wrong because Humayun was her husband; his mother was Maham Begum. B is wrong because Jahangir was her grandson, the son of Akbar and Mariam-uz-Zamani. D is wrong because Babur was her father-in-law, the founder of the Mughal empire. Exam tip: Babur, then Humayun, then Akbar, then Jahangir; Akbar's mother = Hamida Banu Begum, born at Amarkot in 1542.

Q154.Indian HistoryAsked in: RRB Group D · 1 Nov 2018, Shift 1Easy

Akbar followed a policy of religious tolerance and gave the ________ high positions in his court.

  1. A.Muslims
  2. B.Rajputs
  3. C.Sikhs
  4. D.Christians
Show answer

Correct answer: B. Rajputs

Explanation

The correct answer is B, Rajputs. Akbar won over the Rajput rulers through marriage alliances and high ranks, turning old rivals into pillars of the Mughal empire. In 1562 he married the daughter of Raja Bharmal of Amber, and her family rose to the top of the nobility: Raja Man Singh of Amber became one of his greatest generals and governors. Raja Todar Mal, his finance minister, built the land revenue system, and Raja Birbal was among his closest companions. Akbar abolished the pilgrim tax in 1563 and the jizya in 1564, and his idea of sulh-i-kul, peace with all, shaped his rule. A is wrong because Muslim nobles already held high posts; giving them rank was not a sign of tolerance. C is wrong because the Sikhs were a small community under their Gurus then and held no court ranks. D is wrong because Christian Jesuits visited his court for debates but were not given high posts. Exam tip: Akbar's tolerance = Rajput alliances, jizya abolished in 1564, sulh-i-kul, Ibadat Khana at Fatehpur Sikri.

Q155.Indian PolityAsked in: RRB Group D · 3 Oct 2018, Shift 2Easy

Part IV of the Indian Constitution deals with __________.

  1. A.Directive Principles of State Policy
  2. B.Human Rights
  3. C.The Union Judiciary
  4. D.Parliament
Show answer

Correct answer: A. Directive Principles of State Policy

Explanation

The correct answer is A, Directive Principles of State Policy. Part IV, Articles 36 to 51, lists the Directive Principles that guide the State in making laws for a welfare state. The idea was borrowed from the Constitution of Ireland, which in turn took it from Spain. These principles cannot be enforced by any court, but Article 37 says they are fundamental to the governance of the country. Examples are equal pay for equal work, a uniform civil code (Article 44), free legal aid (Article 39-A), village panchayats (Article 40) and protection of the environment and wildlife (Article 48-A). B is wrong because the Constitution has no part named Human Rights; the enforceable rights are the Fundamental Rights in Part III. C is wrong because the Union Judiciary, meaning the Supreme Court, comes under Chapter IV of Part V. D is wrong because Parliament is covered by Chapter II of Part V. Exam tip: Part III = Fundamental Rights (enforceable), Part IV = Directive Principles (not enforceable), Part IV-A = Fundamental Duties.

Q156.Indian PolityAsked in: RRB Group D · 26 Aug 2022, Shift 1Medium

Which of the following schedules of the Indian Constitution describes the number of seats represented in the Council of States from each state and Union Territory?

  1. A.First Schedule
  2. B.Fourth Schedule
  3. C.Third Schedule
  4. D.Second Schedule
Show answer

Correct answer: B. Fourth Schedule

Explanation

The correct answer is B, Fourth Schedule. The Fourth Schedule allots the seats of the Rajya Sabha, the Council of States, among the States and Union Territories. Uttar Pradesh gets the most with 31, followed by Maharashtra with 19 and Tamil Nadu with 18, while small states such as Goa, Sikkim and Mizoram get one seat each. Article 80 fixes the House at not more than 250 members, 12 of them nominated by the President for their work in literature, science, art and social service. Members are elected by the State Legislative Assemblies by proportional representation and serve six years, with one-third retiring every two years. A is wrong because the First Schedule lists the States and Union Territories and their territories. C is wrong because the Third Schedule contains the forms of oaths and affirmations. D is wrong because the Second Schedule gives the salaries and allowances of the President, Governors, judges and other officials. Exam tip: Schedule 1 = States and UTs, Schedule 2 = salaries, Schedule 3 = oaths, Schedule 4 = Rajya Sabha seats.

Q157.Indian PolityAsked in: RRB Group D · 30 Sep 2022, Shift 3Medium

Under which Article of the Constitution of India do we consider Hindi in Devanagari script as an official language of India?

  1. A.Article 351
  2. B.Article 336
  3. C.Article 343
  4. D.Article 347
Show answer

Correct answer: C. Article 343

Explanation

The correct answer is C, Article 343. Article 343(1) declares that the official language of the Union shall be Hindi in the Devanagari script, with the international form of Indian numerals for official purposes. Part XVII of the Constitution, Articles 343 to 351, deals with official language. Article 343 allowed English to continue for fifteen years from 1950, and the Official Languages Act of 1963 kept English alongside Hindi after that period. Article 344 provides for a Commission and a Committee of Parliament on official language, and the Eighth Schedule lists the languages recognised by the Constitution. A is wrong because Article 351 is only a directive to promote and develop Hindi. B is wrong because Article 336 gives a special provision for the Anglo-Indian community in certain services. D is wrong because Article 347 lets the President recognise a language spoken by a section of a State's population. Exam tip: Article 343 = Hindi in Devanagari as the official language; Article 351 = directive to develop Hindi; Articles 343 to 351 make up Part XVII.

Q158.Indian PolityAsked in: RRB Group D · 27 Sep 2022, Shift 3Medium

In which of the following years was Article 21-A inserted in the Constitution of India, which deals with the Fundamental Right of getting compulsory education for all children in the age group of six to fourteen years?

  1. A.2003
  2. B.2004
  3. C.2001
  4. D.2002
Show answer

Correct answer: D. 2002

Explanation

The correct answer is D, 2002. Article 21-A was inserted by the Constitution (86th Amendment) Act, 2002, making free and compulsory education for children aged six to fourteen a Fundamental Right. The same amendment added a new Fundamental Duty in Article 51-A(k), asking parents and guardians to provide education to their children, and reworded Article 45 to cover early childhood care for children below six years. The law that puts Article 21-A into practice is the Right of Children to Free and Compulsory Education (RTE) Act, 2009, which came into force on 1 April 2010. A is wrong because 2003 saw no amendment on education. B is wrong because 2004 is not linked to Article 21-A. C is wrong because 2001 is before the amendment was passed. Exam tip: 86th Amendment 2002 = Article 21-A; RTE Act 2009, enforced from 1 April 2010; age group 6 to 14 years.

Q159.Indian PolityAsked in: RRB Group D · 16 Sep 2022, Shift 3Medium

The executive power of the State shall be vested in the Governor and shall be exercised by him either directly or through officers subordinate to him in accordance with which Article of the Constitution of India?

  1. A.Article 124
  2. B.Article 134
  3. C.Article 144
  4. D.Article 154
Show answer

Correct answer: D. Article 154

Explanation

The correct answer is D, Article 154. Article 154 says the executive power of a State is vested in the Governor, who exercises it directly or through officers under him, exactly as Article 53 does for the President at the Centre. Part VI of the Constitution deals with the States: Article 153 provides a Governor for each State, Article 155 says the President appoints the Governor, Article 156 fixes the term at five years, and Article 163 gives the Governor a Council of Ministers to aid and advise him. In practice the Chief Minister and the ministers run the government, and the Governor acts on their advice. A is wrong because Article 124 establishes the Supreme Court. B is wrong because Article 134 deals with criminal appeals to the Supreme Court. C is wrong because Article 144 requires all authorities to act in aid of the Supreme Court. Exam tip: Article 53 = President's executive power, Article 154 = Governor's executive power; the two Articles mirror each other.

Q160.General ScienceAsked in: RRB Group D · 19 Sep 2022, Shift 3Easy

What is the unit of magnification?

  1. A.Dioptre
  2. B.Newton
  3. C.cm
  4. D.It has no unit
Show answer

Correct answer: D. It has no unit

Explanation

The correct answer is D, It has no unit. Magnification is a ratio of two lengths, so the units cancel and it is a pure number. For a mirror or a lens, magnification m equals the height of the image divided by the height of the object (h′/h). For a lens it also equals v/u, the image distance divided by the object distance, and for a mirror it equals −v/u. A value of 2 means the image is twice the size of the object; a value less than 1 means it is smaller. With the usual sign convention a negative m means a real, inverted image, and a positive m means a virtual, erect image. A is wrong because the dioptre is the unit of the power of a lens, P = 1/f with f in metres. B is wrong because the newton is the SI unit of force. C is wrong because the centimetre measures lengths such as focal length and image distance, not their ratio. Exam tip: magnification = no unit; power of a lens = dioptre; focal length = metre or centimetre.