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GATE 2021 CE (Set 1) question paper PDF and answer key

The official GATE 2021 Civil Engineering (Set 1) paper, organised by IIT Bombay: 65 questions for 100 marks in 3 hours. Download the official question paper and answer key as PDFs. Below is how the marks were split by topic, the complete official answer key and 5 questions solved step by step.

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Question paper (PDF)Official answer key (PDF)

Source: the official paper and answer key published by IIT Bombay for GATE 2021 (official GATE site). Spotted a mistake? Email team@lemyte.com.

General Aptitude
10 · 15 marks
Civil Engineering
55 · 85 marks
MCQ / MSQ / NAT
36 / 1 / 28
Marks to all
None

Where the marks were

GATE 2021 CE (Set 1) topic-wise marks

Civil Engineering questions only; General Aptitude adds 15 marks on top. The top three topics carried 42 of the 85 subject marks.

TopicQuestionsMarks
Structural Engineering1016
Geotechnical Engineering813
Environmental Engineering813
Water Resources Engineering711
Transportation Engineering69
Construction Materials and Management46
Geomatics Engineering34
Numerical Methods24
Probability and Statistics23
Linear Algebra22
Calculus22
Ordinary Differential Equations12

Free solved questions

5 solved questions from GATE 2021 CE (Set 1)

Question text and figures as in the official paper, the answer from the official key, and a worked solution. The other 60 solutions are in your report after you take the paper.

Q7 · General Aptitude · MCQ · 2 marks

Consider two rectangular sheets, Sheet M and Sheet N of dimensions 6 cm x 4 cm each.

Folding operation 1: The sheet is folded into half by joining the short edges of the current shape.

Folding operation 2: The sheet is folded into half by joining the long edges of the current shape.

Folding operation 1 is carried out on Sheet M three times.

Folding operation 2 is carried out on Sheet N three times.

The ratio of perimeters of the final folded shape of Sheet N to the final folded shape of Sheet M is ______.

  • (A)
    13 : 7
  • (B)
    3 : 2
  • (C)
    7 : 5
  • (D)
    5 : 13

Answer (official key): A

Solution

For M, the successive rectangles are 4x3, 3x2 and 2x1.5, so its perimeter is 7 cm. For N, the successive rectangles are 6x2, 6x1 and 6x0.5, so its perimeter is 13 cm. The ratio N:M is 13:7, option A.

Q8 · General Aptitude · MCQ · 2 marks

Figure for GATE 2021 CE (Set 1) question 8 (Spatial Aptitude)

Five line segments of equal lengths, PR, PS, QS, QT and RT are used to form a star as shown in the figure above.

The value of θ\theta, in degrees, is ______

  • (A)
    36
  • (B)
    45
  • (C)
    72
  • (D)
    108

Answer (official key): A

Solution

The five equal segments form a regular five-point star (pentagram). Its five congruent tip angles sum to 180 degrees, so each tip angle is 180/5=36 degrees, option A.

Q27 · Geomatics Engineering · MSQ · 1 mark

Which of the following is/are correct statement(s)?

  • (A)
    Back Bearing of a line is equal to Fore Bearing ± 180°.
  • (B)
    If the whole circle bearing of a line is 270°, its reduced bearing is 90° NW.
  • (C)
    The boundary of water of a calm water pond will represent contour line.
  • (D)
    In the case of fixed hair stadia tachometry, the staff intercept will be larger, when the staff is held nearer to the observation point.

Answer (official key): A, B, C

Solution

A back bearing differs by 180°; 270° converts to N90°W; and a calm-water boundary has constant elevation. In stadia, intercept increases with distance, so D is false. The accepted MSQ set is A, B and C.

Q51 · Structural Engineering · Numerical · 2 marks

Employ stiffness matrix approach for the simply supported beam as shown in the figure to calculate unknown displacements/rotations. Take length, L = 8 m; modulus of elasticity, E = 3×10⁴ N/mm²; moment of inertia, I = 225×10⁶ mm⁴.

Figure for GATE 2021 CE (Set 1) question 51 (Structural Engineering)

The mid-span deflection of the beam (in mm, round off to integer) under P = 100 kN in downward direction will be ________

Answer (official key): 100 to 130

Solution

Using the unit-load integral with a=L/2: left contribution is Pa3/(24EI)Pa^3/(24EI) and right contribution Pa3/(12EI)Pa^3/(12EI). Thus δ=PL3/(64EI)=118.5185\delta=P L^3/(64EI)=118.5185 mm, which rounds to 119 mm.

Q54 · Geotechnical Engineering · Numerical · 2 marks

The soil profile at a construction site is shown in the figure (not to scale). Ground water table (GWT) is at 5 m below the ground level at present. An old well data shows that the ground water table was as low as 10 m below the ground level in the past. Take unit weight of water, γw\gamma_w = 9.81 kN/m³.

Figure for GATE 2021 CE (Set 1) question 54 (Geotechnical Engineering)

The overconsolidation ratio (OCR) (round off to two decimal places) at the mid-point of the clay layer is _____________

Answer (official key): 1.18 to 1.26

Solution

At the midpoint (4 m into clay), present effective stress is 17.5(5)+(18.5−9.81)(10)+(17−9.81)(4)=203.1617.5(5)+(18.5−9.81)(10)+(17−9.81)(4)=203.16 kPa. Historical maximum is 17.5(10)+(18.5−9.81)(5)+(17−9.81)(4)=247.2117.5(10)+(18.5−9.81)(5)+(17−9.81)(4)=247.21 kPa. OCR=247.21/203.16=1.21682≈1.22.

The other 60 questions are solved in your report when you take GATE 2021 CE (Set 1) as a 3-hour test.

Take GATE 2021 CE (Set 1) as a test

Official answer key

GATE 2021 CE (Set 1) answer key

All 65 answers from the official key. Numerical answers are ranges; “or” means the key accepts either answer.

Download the official GATE 2021 CE (Set 1) answer key (PDF)
QTopicTypeMarksAnswer
1Verbal AptitudeMCQ1D
2Spatial AptitudeMCQ1B
3Quantitative AptitudeMCQ1C
4Quantitative AptitudeMCQ1B
5Analytical AptitudeMCQ1C
6Analytical AptitudeMCQ2B
7Spatial AptitudeMCQ2A
8Spatial AptitudeMCQ2A
9Quantitative AptitudeMCQ2B
10Verbal AptitudeMCQ2C
11Linear AlgebraMCQ1B
12Linear AlgebraMCQ1D
13Probability and StatisticsMCQ1D
14Structural EngineeringMCQ1B
15Construction Materials and ManagementMCQ1A
16Construction Materials and ManagementMCQ1A
17Geotechnical EngineeringMCQ1C
18Geotechnical EngineeringMCQ1B
19Water Resources EngineeringMCQ1A
20Water Resources EngineeringMCQ1D
21Environmental EngineeringMCQ1A
22Environmental EngineeringMCQ1B
23Environmental EngineeringMCQ1B
24Transportation EngineeringMCQ1C
25Transportation EngineeringMCQ1B
26Geomatics EngineeringMCQ1A
27Geomatics EngineeringMSQ1A, B, C
28CalculusNumerical10.5
29CalculusNumerical115
30Structural EngineeringNumerical195 to 97
31Structural EngineeringNumerical12
32Structural EngineeringNumerical10.9
33Geotechnical EngineeringNumerical14.8 to 5
34Water Resources EngineeringNumerical12400
35Transportation EngineeringNumerical160.7 to 61.1
36Ordinary Differential EquationsMCQ2A
37Numerical MethodsMCQ2B
38Environmental EngineeringMCQ2C
39Structural EngineeringMCQ2D
40Construction Materials and ManagementMCQ2B
41Geotechnical EngineeringMCQ2A
42Water Resources EngineeringMCQ2A
43Environmental EngineeringMCQ2B
44Environmental EngineeringMCQ2D
45Transportation EngineeringMCQ2D
46Numerical MethodsNumerical220 to 21
47Probability and StatisticsNumerical20.58 to 0.6
48Structural EngineeringNumerical2490 to 510
49Structural EngineeringNumerical20
50Structural EngineeringNumerical227 to 29
51Structural EngineeringNumerical2100 to 130
52Structural EngineeringNumerical22.4 to 2.6
53Construction Materials and ManagementNumerical20
54Geotechnical EngineeringNumerical21.18 to 1.26
55Geotechnical EngineeringNumerical24.2 to 4.35
56Geotechnical EngineeringNumerical25.7 to 5.9
57Geotechnical EngineeringNumerical21.94 to 1.98
58Water Resources EngineeringNumerical22.8 to 2.95
59Water Resources EngineeringNumerical20.35 to 0.4
60Water Resources EngineeringNumerical234 to 38
61Environmental EngineeringNumerical230
62Environmental EngineeringNumerical2375
63Transportation EngineeringNumerical255.5 to 58.5
64Transportation EngineeringNumerical20.3 to 0.34
65Geomatics EngineeringNumerical2196 or 218

Questions about GATE 2021 CE (Set 1)

How many questions are in the GATE 2021 CE (Set 1) paper?

65 questions for 100 marks: 10 General Aptitude questions worth 15 marks and 55 Civil Engineering questions worth 85 marks. By type, there were 36 MCQs, 1 MSQs, 28 numerical answer (NAT) questions. The paper lasted 3 hours.

Is there negative marking in GATE 2021 CE (Set 1)?

Yes, for MCQs only. A wrong MCQ answer costs one-third of its marks (−⅓ for a 1-mark question, −⅔ for a 2-mark question). MSQ and numerical (NAT) questions have no negative marking, and an MSQ earns marks only when every correct option is chosen.

Which topics carried the most marks in GATE 2021 CE (Set 1)?

Outside General Aptitude, the biggest topics were Structural Engineering (16 marks), Geotechnical Engineering (13 marks), Environmental Engineering (13 marks). The full topic-wise split is in the table on this page.

Were any GATE 2021 CE (Set 1) questions awarded marks to all?

No. Every question was graded with the answer in the official key.

Where does this GATE 2021 CE (Set 1) answer key come from?

From the official answer key published by IIT Bombay, which organised GATE 2021. Range answers for numerical questions and questions with more than one accepted answer are kept exactly as the key gives them.

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