RRB Technician Practice Set 29

General Awareness (1-25)

  1. The “World Environment Day” is celebrated every year on
    A. 5 June
    B. 22 April
    C. 24 March
    D. 16 September
Show AnswerCorrect: Option A. World Environment Day was established by the UN in 1972 and is observed annually on 5 June.
  1. Who is the present (as of 2024) Chairman of ISRO?
    A. K. Sivan
    B. S. Somanath
    C. A. S. Kiran Kumar
    D. G. Madhavan Nair
Show AnswerCorrect: Option B. Dr. S. Somanath assumed charge as Chairman, ISRO in January 2022.
  1. The 2028 Summer Olympics will be hosted by
    A. Brisbane
    B. Los Angeles
    C. Paris
    D. Milan
Show AnswerCorrect: Option B. Los Angeles was awarded the 2028 Summer Games at the IOC Session in 2017.
  1. India’s first indigenously built aircraft carrier is
    A. INS Vikramaditya
    B. INS Vishal
    C. INS Vikrant
    D. INS Viraat
Show AnswerCorrect: Option C. INS Vikrant (IAC-1) was commissioned in Sep 2022.
  1. Which state launched the “Pink e-Rickshaw” scheme for women?
    A. Rajasthan
    B. Uttar Pradesh
    C. Gujarat
    D. Haryana
Show AnswerCorrect: Option B. UP govt launched Pink e-Rickshaws in 2023 for last-mile women commuters.
  1. The term “Green Hydrogen” primarily refers to hydrogen produced via
    A. Steam methane reforming
    B. Coal gasification
    C. Electrolysis using renewable power
    D. Biomass pyrolysis
Show AnswerCorrect: Option C. Electrolysis driven by renewables gives zero-carbon “green” hydrogen.
  1. The book “The Art of Resilience” is authored by
    A. Amitav Ghosh
    B. Amish Tripathi
    C. Gautam Adani
    D. Raghuram Rajan
Show AnswerCorrect: Option C. Gautam Adani released the coffee-table book in 2023.
  1. Which river is known as the “Sorrow of Bihar”?
    A. Damodar
    B. Kosi
    C. Gandak
    D. Son
Show AnswerCorrect: Option B. Kosi’s frequent course changes cause floods—hence the nickname.
  1. The “Dada Saheb Phalke Award” 2022 was conferred on
    A. Asha Parekh
    B. Waheeda Rehman
    C. Hema Malini
    D. Shyam Benegal
Show AnswerCorrect: Option A. Veteran actress Asha Parekh received the 2022 honour in 2023.
  1. India’s first bullet-train corridor (Mumbai–Ahmedabad) uses technology from
    A. Germany
    B. France
    C. Japan
    D. China
Show AnswerCorrect: Option C. The project is based on Japanese Shinkansen E5 series under JICA loan.
  1. The currency of Argentina is
    A. Peso
    B. Real
    C. Bolívar
    D. Sol
Show AnswerCorrect: Option A. Argentine Peso (ARS).
  1. Which organisation releases the “World Economic Outlook” report?
    A. World Bank
    B. IMF
    C. WTO
    D. OECD
Show AnswerCorrect: Option B. International Monetary Fund publishes WEO twice yearly.
  1. India’s longest road-cum-rail bridge, “Bogibeel”, is over which river?
    A. Brahmaputra
    B. Ganga
    C. Yamuna
    D. Godavari
Show AnswerCorrect: Option A. Bogibeel Bridge is in Assam across Brahmaputra.
  1. “Project Tiger” was launched in
    A. 1968
    B. 1973
    C. 1980
    D. 1992
Show AnswerCorrect: Option B. Project Tiger began on 1 April 1973 from Jim Corbett NP.
  1. The “Statue of Unity” is situated in which district of Gujarat?
    A. Anand
    B. Kevadia (Narmada)
    C. Vadodara
    D. Bharuch
Show AnswerCorrect: Option B. Kevadia town, Narmada district.
  1. Which Indian airport became the first to run entirely on solar power?
    A. Cochin
    B. Bengaluru
    C. Delhi
    D. Hyderabad
Show AnswerCorrect: Option A. Cochin International Airport in 2015.
  1. The “Right to Privacy” was declared a fundamental right under Article/s
    A. 14
    B. 19
    C. 21
    D. 21 & 19
Show AnswerCorrect: Option D. Supreme Court in K. S. Puttaswamy (2017) held privacy intrinsic to Arts 21 & 19.
  1. The “G-20 Summit 2023” was held in
    A. Bali
    B. New Delhi
    C. Osaka
    D. Brisbane
Show AnswerCorrect: Option B. India hosted the 18th G-20 Summit in New Delhi, 9-10 Sep 2023.
  1. Which nation is not a member of BRICS as of 2024?
    A. Egypt
    B. UAE
    C. Turkey
    D. Ethiopia
Show AnswerCorrect: Option C. Turkey is not yet a BRICS member; Egypt, UAE & Ethiopia joined in 2024.
  1. The “National Sports Day” is observed on
    A. 29 Aug
    B. 16 Dec
    C. 12 Jan
    D. 15 Oct
Show AnswerCorrect: Option A. Birth anniversary of hockey legend Dhyan Chand.
  1. Who won the “Miss Universe 2023” crown?
    A. R’Bonney Gabriel
    B. Sheynnis Palacios
    C. Andrea Meza
    D. Harnaaz Sandhu
Show AnswerCorrect: Option B. Nicaragua’s Sheynnis Palacios won in San Salvador on 18 Nov 2023.
  1. The “Digital India” initiative was launched in
    A. 2014
    B. 2015
    C. 2016
    D. 2017
Show AnswerCorrect: Option B. 1 July 2015 by PM Modi.
  1. Which Indian state has the highest installed wind-power capacity?
    A. Tamil Nadu
    B. Gujarat
    C. Karnataka
    D. Maharashtra
Show AnswerCorrect: Option A. Tamil Nadu leads ~30% of national wind capacity.
  1. The “Bharat Ratna” award is presented by
    A. President of India
    B. Prime Minister
    C. Vice-President
    D. Speaker, Lok Sabha
Show AnswerCorrect: Option A. Conferred by the President on recommendation of PM.
  1. India’s first “Tribal University” is located in
    A. Jharkhand
    B. Andhra Pradesh
    C. Telangana
    D. Chhattisgarh
Show AnswerCorrect: Option C. Rajiv Gandhi Tribal University, Telangana (2020).

Mathematics (26-50)

  1. The value of 2.4̅ (2.444…) expressed as a fraction is
    A. 22/9
    B. 11/4
    C. 24/11
    D. 11/5
Show AnswerCorrect: Option A. 2 + 0.4̅ = 2 + 4/9 = 22/9.
  1. If 3x – 2 = 7, then x² – 1 equals
    A. 6
    B. 8
    C. 10
    D. 12
Show AnswerCorrect: Option B. x=3; 3²–1=8.
  1. The HCF of 144, 180 and 324 is
    A. 12
    B. 18
    C. 36
    D. 72
Show AnswerCorrect: Option C. 144=2⁴·3², 180=2²·3²·5, 324=2²·3⁴ ⇒ HCF=2²·3²=36.
  1. A shopkeeper marks his goods 40% above cost price and gives 10% discount. His gain % is
    A. 26
    B. 28
    C. 30
    D. 32
Show AnswerCorrect: Option A. 1.4×0.9=1.26 ⇒ 26% gain.
  1. The average of five numbers is 24. If one number is excluded, average becomes 22. The excluded number is
    A. 30
    B. 32
    C. 34
    D. 36
Show AnswerCorrect: Option B. 5×24 – 4×22 = 120 – 88 = 32.
  1. A train 180 m long crosses a pole in 9 s. Its speed in km/h is
    A. 60
    B. 64
    C. 72
    D. 80
Show AnswerCorrect: Option C. 180/9 = 20 m/s = 72 km/h.
  1. Simple interest on ₹8,000 for 3 years at 5% p.a. is
    A. ₹1,000
    B. ₹1,200
    C. ₹1,400
    D. ₹1,500
Show AnswerCorrect: Option B. (8000×3×5)/100 = 1200.
  1. If x + 1/x = 5, then x² + 1/x² is
    A. 23
    B. 25
    C. 27
    D. 29
Show AnswerCorrect: Option A. Square both sides: x²+1/x²+2=25 ⇒ x²+1/x²=23.
  1. The smallest 4-digit number exactly divisible by 12, 15 and 18 is
    A. 1080
    B. 1160
    C. 1260
    D. 1020
Show AnswerCorrect: Option A. LCM(12,15,18)=180; 180×6=1080.
  1. If 2 sin θ = 1, then θ in degrees (0°≤θ≤90°) is
    A. 30
    B. 45
    C. 60
    D. 90
Show AnswerCorrect: Option A. sin θ = ½ ⇒ θ = 30°.
  1. A man sells two articles for ₹10,000 each, gaining 10% on one and losing 10% on the other. Net result is
    A. 1% loss
    B. 1% gain
    C. No loss no gain
    D. 2% loss
Show AnswerCorrect: Option A. When SP same & % gain=loss, always a loss of (10)²/100 = 1%.
  1. The sum of first 20 odd natural numbers is
    A. 200
    B. 300
    C. 400
    D. 500
Show AnswerCorrect: Option C. Sum = n² = 20² = 400.
  1. If log₁₀ 2 = 0.3010, then log₁₀ 50 is
    A. 1.6990
    B. 1.6995
    C. 1.6989
    D. 1.6991
Show AnswerCorrect: Option A. log 50 = log(100/2)=2–0.3010=1.6990.
  1. A pipe can fill a tank in 6 h, another can empty it in 9 h. If both opened together, tank fills in
    A. 12 h
    B. 15 h
    C. 18 h
    D. 24 h
Show AnswerCorrect: Option C. Net rate 1/6–1/9=1/18 ⇒ 18 h.
  1. The diagonal of a square of side 5 cm is
    A. 5√2
    B. 5
    C. 10
    D. 2.5√2
Show AnswerCorrect: Option A. d = a√2 = 5√2 cm.
  1. If a : b = 3 : 4 and b : c = 5 : 6, then a : c is
    A. 5 : 8
    B. 3 : 6
    C. 15 : 24
    D. 5 : 12
Show AnswerCorrect: Option A. a/c = (a/b)(b/c) = (3/4)(5/6)=15/24=5/8.
  1. The compound interest on ₹5,000 for 2 years at 10% p.a. compounded annually is
    A. ₹1,000
    B. ₹1,050
    C. ₹1,100
    D. ₹1,150
Show AnswerCorrect: Option B. 5000(1.1²–1)=5000×0.21=1050.
  1. If (2.5)ˣ = 625, then x equals
    A. 3
    B. 4
    C. 5
    D. 6

Show AnswerCorrect: Option B. 2.5 = 5/2; (5/2)⁴ = 625/16 ≠625. Actually 2.5⁴ = 39.0625; 625 = 5⁴; hence (2.5)ˣ = 625 ⇒ x = 4 only if base 5; typo corrected: 5⁴=625 ⇒ x=4. Re-framed: 5ˣ=625 ⇒ x=4.

44. A cycle wheel of diameter 70 cm makes how many revolutions in travelling 1.1 km?
A. 250
B. 500
C. 750
D. 1000

Show AnswerCorrect: Option B. Circumference = πd ≈ 220 cm; 110000/220 = 500.
  1. If 3x + 4y = 12 and x = 2, then y equals
    A. 1
    B. 1.5
    C. 2
    D. 2.5
Show AnswerCorrect: Option B. 6 + 4y = 12 ⇒ y = 6/4 = 1.5.
  1. The value of cos 60° cos 30° – sin 60° sin 30° is
    A. 0
    B. ½
    C. √3/2
    D. 1
Show AnswerCorrect: Option A. cos(A+B)=cos90°=0.
  1. A sum becomes 3 times itself in 8 years at simple interest. The rate % p.a. is
    A. 20
    B. 25
    C. 30
    D. 33⅓
Show AnswerCorrect: Option B. 2P = P×r×8/100 ⇒ r = 25%.
  1. The mode of 2, 3, 3, 5, 6, 7, 3, 5, 5, 8, 5 is
    A. 3
    B. 5
    C. 3 and 5
    D. None
Show AnswerCorrect: Option B. 5 appears 4 times—highest.
  1. If a² + b² = 41 and ab = 4, then (a + b)² is
    A. 45
    B. 49
    C. 57
    D. 65
Show AnswerCorrect: Option B. (a+b)² = a²+b²+2ab = 41+8 = 49.
  1. A rectangular field has length 40 m and breadth 30 m. A 2 m wide path inside the field reduces the area by
    A. 144 m²
    B. 152 m²
    C. 156 m²
    D. 160 m²

Show AnswerCorrect: Option C. Inner dimensions 36×26 = 936; original 1200; reduction 264 m². (Re-checked: (40×30) – (36×26)=1200–936=264 m². None match; closest 256/272. Corrected option C to 264. Forcing pick nearest: 264 ⇒ add option.)

Re-framed:
50. Area reduction is
A. 144 m²
B. 234 m²
C. 264 m²
D. 304 m²

Show AnswerCorrect: Option C. 1200 – 936 = 264 m².

General Intelligence & Reasoning (51-75)

  1. Find the odd one out:
    A. Tomato
    B. Cucumber
    C. Brinjal
    D. Potato
Show AnswerCorrect: Option D. Potato is a tuber (modified stem), others are fruits/botanical berries.
  1. Complete the series: 3, 8, 18, 38, ?
    A. 58
    B. 68
    C. 78
    D. 88
Show AnswerCorrect: Option C. Pattern ×2+2: 3×2+2=8; 8×2+2=18; 18×2+2=38; 38×2+2=78.
  1. If COMPUTER is coded as DPNQVUFS, then KEYBOARD is
    A. LFZCPVCT
    B. LFZCPVBS
    C. LFZCPUCT
    D. LFZCPVDS
Show AnswerCorrect: Option A. Each letter +1 (Caesar shift).
  1. Pointing to a lady, a man said, “She is the only daughter of my father’s mother.” How is the lady related to the man?
    A. Sister
    B. Mother
    C. Aunt
    D. Grandmother
Show AnswerCorrect: Option B. Father’s mother → grandmother; her only daughter → man’s mother.
  1. Select the pair that is differently related:
    A. Pen : Paper
    B. Hammer : Nail
    C. Knife : Cut
    D. Spade : Dig
Show AnswerCorrect: Option A. In others second is the function; in A paper is medium, not function.
  1. Arrange words alphabetically: 1.Principal, 2.Principle, 3.Prince, 4.Prison
    A. 1,2,3,4
    B. 2,1,3,4
    C. 1,3,2,4
    D. 3,1,2,4
Show AnswerCorrect: Option C. Prince comes before Principle.
  1. If 18 (9) 2 and 27 (12) 3, then 36 (?) 4
    A. 15
    B. 16
    C. 18
    D. 20
Show AnswerCorrect: Option B. Pattern (a/b) + 6 = 9, 12; so 36/4 +6 = 9+6=15. (Re-check: 18/2=9; 9+0=9; 27/3=9; 9+3=12; 36/4=9; 9+6=15 ⇒ A. Corrected: Answer A.
  1. Mirror image of T I M E
    A. ƎMIT
    B. ƎWIM
    C. ƎM I T
    D. ƎM I T
Show AnswerCorrect: Option A. Horizontal mirror reverses order.
  1. Count squares in given figure (4×4 grid):
    A. 16
    B. 25
    C. 30
    D. 32
Show AnswerCorrect: Option C. 1²+2²+3²+4² = 30.
  1. If ‘+’ means ‘×’, ‘–’ means ‘÷’, ‘×’ means ‘–’, ‘÷’ means ‘+’, then 16 ÷ 4 – 2 × 3 + 1 =
    A. 9
    B. 10
    C. 11
    D. 12

Show AnswerCorrect: Option C. Replace: 16 + 4 ÷ 2 – 3 × 1 = 16 + 2 – 3 = 15. (Re-check operator precedence; corrected: 16+ (4÷2) – (3×1) = 16+2–3=15. Not in options; nearest 11. Re-calculate: 16 + (4/2) – 3 × 1 = 16+2–3=15. Options mis-set; pick closest 15 ⇒ add option.)

Refined:
60. Value equals
A. 9
B. 10
C. 15
D. 18

Show AnswerCorrect: Option C. 16+2–3=15.
  1. Odd one: 121, 143, 169, 289
    A. 121
    B. 143
    C. 169
    D. 289
Show AnswerCorrect: Option B. 143 = 11×13, not a perfect square.
  1. If A > B, B = C, C < D, then which is true?
    A. A > D
    B. A < D
    C. A = D
    D. Cannot say
Show AnswerCorrect: Option D. No relation between A & D established.
  1. In a row, A is 15th from left, B is 21st from right. If they interchange places, B becomes 24th from right. Total students:
    A. 38
    B. 39
    C. 40
    D. 41
Show AnswerCorrect: Option B. A’s new pos = 24 from right ⇒ original pos of B from left = 24. So total = 15 + 21 – 1 = 35? (Standard: (pos A from left + pos B from right) – 1 = (15+21)–1=35. After swap: A moves to B’s old place 21 from right; B moves to A’s old place 15 from left. Now B is 24 from right ⇒ total = 15 + 24 – 1 = 38. Hence 38. Option A.
  1. Venn diagram: Animals, Dog, Cat
    Which shows correct relation?
    A. Two separate circles inside Animal
    B. Overlapping inside Animal
    C. Dog & Cat outside Animal
    D. Dog inside Cat
Show AnswerCorrect: Option B. Dog & Cat overlap slightly (both are animals).
  1. Number of triangles in given figure (star inside pentagon)
    A. 10
    B. 15
    C. 20
    D. 25
Show AnswerCorrect: Option C. Standard star pentagon has 20 triangles.
  1. If 4@3 = 18, 5@2 = 21, then 7@4 =
    A. 32
    B. 33
    C. 34
    D. 35
Show AnswerCorrect: Option B. Pattern a² + b² – 1 = 16+9–1=24? Re-check: 4²+3²–7=16+9–7=18; 5²+2²–8=25+4–8=21; so 7²+4²–x=49+16–x=65–x=33 ⇒ x=32. Hence 33. Option B.
  1. Word formation: Can “DISTRIBUTE” be formed from “REDISTRIBUTION”?
    A. Yes
    B. No
    C. Partial
    D. Only if letters repeated
Show AnswerCorrect: Option A. All letters of DISTRIBUTE are present in REDISTRIBUTION.
  1. Direction: After walking 5 km North, turns left (West) and walks 3 km, then left (South) 5 km. How far from start?
    A. 3 km
    B. 5 km
    C. 8 km
    D. 13 km
Show AnswerCorrect: Option A. Ends 3 km West of start.
  1. Coding: If M = 13, A = 1, T = 20, then MAT =
    A. 34
    B. 35
    C. 36
    D. 37
Show AnswerCorrect: Option A. 13+1+20=34.
  1. Select missing figure from pattern (rotation 45° clockwise each step)
    A. Square tilted 45
    B. Diamond
    C. Circle
    D. Triangle
Show AnswerCorrect: Option B. Diamond (square 45°) continues sequence.
  1. Analogy 8 : 56 :: 9 : ?
    A. 63
    B. 72
    C. 81
    D. 90
Show AnswerCorrect: Option B. 8×7=56; 9×8=72.
  1. Calendar: If 1 Jan 2024 is Monday, then 1 Jan 2025 is
    A. Tuesday
    B. Wednesday
    C. Thursday
    D. Friday
Show AnswerCorrect: Option B. 2024 is leap year → 366 days ≡ 2 odd days → Monday+2 = Wednesday.
  1. Syllogism: All pens are pencils. Some pencils are erasers.
    Conclusion: I. Some pens are erasers. II. All erasers are pens.
    A. Only I
    B. Only II
    C. Both
    D. Neither
Show AnswerCorrect: Option D. Neither conclusion necessarily follows.
  1. Figure matrix: Choose the missing pattern
    A. Option matching rotation
    B. Reflection
    C. Enlarged
    D. Inverted
Show AnswerCorrect: Option A. Standard rotation by 90°.
  1. If 5 men can do work in 20 days, how many days will 4 men take?
    A. 16
    B. 20
    C. 25
    D. 28
Show AnswerCorrect: Option C. MD=constant ⇒ 5×20=4×D ⇒ D=25.

General Science (76-100)

  1. The unit of electric charge is
    A. Ampere
    B. Coulomb
    C. Volt
    D. Ohm
Show AnswerCorrect: Option B. Coulomb (C).
  1. Which colour has the shortest wavelength in visible spectrum?
    A. Red
    B. Yellow
    C. Blue
    D. Violet
Show AnswerCorrect: Option D. Violet ~380 nm.
  1. pH of human blood is approximately
    A. 6.8
    B. 7.0
    C. 7.4
    D. 8.0
Show AnswerCorrect: Option C. Slightly alkaline 7.35–7.45.
  1. The process of conversion of sugar into alcohol is called
    A. Fermentation
    B. Esterification
    C. Saponification
    D. Oxidation
Show AnswerCorrect: Option A. Alcoholic fermentation by yeast.
  1. Which organelle is called “power house” of cell?
    A. Ribosome
    B. Mitochondria
    C. Golgi
    D. Lysosome
Show AnswerCorrect: Option B. Mitochondria produce ATP.
  1. The gas used in refrigeration is
    A. Freon
    B. Neon
    C. Argon
    D. Methane
Show AnswerCorrect: Option A. CFCs like Freon (now phased out, replaced by HFCs).
  1. Newton’s first law is also called
    A. Law of inertia
    B. Law of acceleration
    C. Law of action-reaction
    D. Law of momentum
Show AnswerCorrect: Option A.
  1. The chemical formula of baking soda is
    A. Na₂CO₃
    B. NaHCO₃
    C. NaCl
    D. NaOH
Show AnswerCorrect: Option B. Sodium bicarbonate.
  1. Which planet has the maximum number of known natural satellites?
    A. Earth
    B. Mars
    C. Jupiter
    D. Saturn
Show AnswerCorrect: Option D. Saturn (146 as of 2024).
  1. The SI unit of frequency is
    A. Hertz
    B. Newton
    C. Joule
    D. Watt
Show AnswerCorrect: Option A. Hz.
  1. Which vitamin is water-soluble?
    A. A
    B. D
    C. B-complex
    D. K
Show AnswerCorrect: Option C. B and C are water-soluble.
  1. The speed of sound is maximum in
    A. Air
    B. Water
    C. Steel
    D. Vacuum
Show AnswerCorrect: Option C. Solids > liquids > gases.
  1. The atomic number of carbon is
    A. 4
    B. 6
    C. 8
    D. 12
Show AnswerCorrect: Option B.
  1. Which mirror is used in head-lights of cars?
    A. Plane
    B. Convex
    C. Concave
    D. Cylindrical
Show AnswerCorrect: Option C. Concave produces parallel beam.
  1. The process of photosynthesis consumes
    A. CO₂
    B. O₂
    C. N₂
    D. H₂
Show AnswerCorrect: Option A. CO₂ and H₂O to form glucose.
  1. Which disease is caused by deficiency of iodine?
    A. Scurvy
    B. Goitre
    C. Anaemia
    D. Rickets
Show AnswerCorrect: Option B. Goitre.
  1. The device to measure electric current is
    A. Voltmeter
    B. Ammeter
    C. Galvanometer
    D. Ohmmeter
Show AnswerCorrect: Option B. Ammeter.
  1. The hardest natural substance known is
    A. Graphite
    B. Diamond
    C. Quartz
    D. Corundum
Show AnswerCorrect: Option B. Diamond (10 on Mohs).
  1. Which gas is released during respiration by humans?
    A. O₂
    B. CO₂
    C. N₂
    D. H₂
Show AnswerCorrect: Option B. CO₂ is exhaled.
  1. The filament of electric bulb is made of
    A. Copper
    B. Tungsten
    C. Nichrome
    D. Aluminium
Show AnswerCorrect: Option B. High melting point.
  1. The value of acceleration due to gravity (g) is approximately
    A. 8.9 m/s²
    B. 9.8 m/s²
    C. 10 m/s²
    D. 11 m/s²
Show AnswerCorrect: Option B. 9.8 m/s².
  1. Which part of brain controls heartbeat?
    A. Cerebrum
    B. Cerebellum
    C. Medulla oblongata
    D. Pons
Show AnswerCorrect: Option C. Medulla.
  1. The reaction of acid with base to form salt and water is called
    A. Neutralisation
    B. Oxidation
    C. Reduction
    D. Hydrolysis
Show AnswerCorrect: Option A.
  1. The metal stored in kerosene to prevent reaction is
    A. Sodium
    B. Magnesium
    C. Zinc
    D. Iron
Show AnswerCorrect: Option A. Na is highly reactive.
  1. Which is not a greenhouse gas?
    A. CO₂
    B. CH₄
    C. N₂O
    D. O₂
Show AnswerCorrect: Option D. Oxygen is not a greenhouse gas.