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Tamil Nadu HSE First Year Basic Civil Engineering study materials
Tamil Nadu HSE First Year Basic Civil Engineering study resources

Tamil Nadu HSE First Year Basic Civil Engineering practice questions

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Question 1Introduction to Civil Engineering and Engineering Materials

Which branch of civil engineering deals with the planning, design and construction of roads, highways and pavements?

  1. Structural engineering
  2. Transportation engineering Correct answer.
  3. Environmental engineering
  4. Geotechnical engineering

Explanation

Transportation engineering covers the planning, geometric design, construction and maintenance of roads, highways, railways and pavements, including traffic studies and pavement materials. Structural engineering concerns load-bearing frames such as buildings and bridges, while geotechnical and environmental branches handle soil behaviour and water/waste treatment respectively.

Question 2Introduction to Civil Engineering and Engineering Materials

In a building, the structural member that carries the weight of the wall above an opening such as a door or window is called a:

  1. Plinth
  2. Coping
  3. Parapet
  4. Lintel Correct answer.

Explanation

A lintel is a horizontal structural member placed across an opening in a wall to support the masonry above it and transfer that load to the adjacent wall portions. The plinth is the portion of the wall between the ground and the floor level, a parapet is a low protective wall at the roof edge, and coping is the capping on top of a wall.

Question 3Introduction to Civil Engineering and Engineering Materials

Which of the following is a ferrous material commonly used for structural steel sections in civil engineering construction?

  1. Bitumen
  2. Gypsum
  3. Mild steel Correct answer.
  4. Lime

Explanation

Mild steel is an iron-carbon alloy with low carbon content (about 0.15 to 0.25 per cent), making it ductile and suitable for rolled sections, reinforcement bars and general structural work. Lime, gypsum and bitumen are non-ferrous binding or surfacing materials and contain no iron as their base.

Question 4Introduction to Civil Engineering and Engineering Materials

The property of a building material that allows it to return to its original shape after the load causing deformation is removed is termed:

  1. Ductility
  2. Plasticity
  3. Brittleness
  4. Elasticity Correct answer.

Explanation

Elasticity is the ability of a material to regain its original dimensions on removal of the deforming load, and the maximum stress up to which this occurs is the elastic limit. Plasticity refers to permanent deformation without recovery, ductility is the capacity to be drawn into wires, and brittleness is failure with little deformation.

Question 5Introduction to Civil Engineering and Engineering Materials

Which surveying instrument is used primarily to measure horizontal and vertical angles with high precision at a station?

  1. Plane table
  2. Levelling staff
  3. Clinometer
  4. Theodolite Correct answer.

Explanation

A theodolite is a precision optical instrument with a telescope mounted on horizontal and vertical axes, allowing accurate measurement of horizontal and vertical angles. A levelling staff is a graduated rod used with a level, a plane table is a drawing board for graphical surveying, and a clinometer measures only slope angles.

Question 6Introduction to Civil Engineering and Engineering Materials

The main function of cement in a concrete mix is to:

  1. Provide the bulk volume and resist abrasion
  2. Act as a binding agent that hardens and holds the aggregates together Correct answer.
  3. Supply the water needed for workability
  4. Fill the voids between coarse aggregate particles

Explanation

Cement reacts chemically with water in the hydration process to form a hardened paste that binds the fine and coarse aggregates into a solid mass. The aggregates supply bulk and volume, water provides workability and takes part in hydration, and void filling is achieved by the grading of fine aggregate.

Question 7Introduction to Civil Engineering and Engineering Materials

Which of the following is a natural construction material obtained directly from trees and used for doors, windows and formwork?

  1. Timber Correct answer.
  2. Fly ash
  3. PVC
  4. Glass

Explanation

Timber is wood obtained from trees and used in its natural or seasoned form for doors, windows, shuttering and roofing. Fly ash is an industrial by-product of coal combustion, glass is manufactured by melting silica, and PVC is a synthetic polymer, so none of these is obtained directly from trees.

Question 8Introduction to Civil Engineering and Engineering Materials

A simply supported beam of span 4 m carries a central point load of 20 kN. What is the bending moment at the centre of the span?

  1. 20 kN m Correct answer.
  2. 10 kN m
  3. 80 kN m
  4. 40 kN m

Explanation

For a simply supported beam with a central point load W over span L, each reaction equals W/2, and the maximum bending moment at mid-span is WL/4. Substituting W = 20 kN and L = 4 m gives 20 × 4 / 4 = 20 kN m. The value 40 kN m would arise only if the load were placed at a support, which gives zero moment there.

Question 9Introduction to Civil Engineering and Engineering Materials

A mortar mix is prepared with 1 part cement to 6 parts sand by volume. Why is such a lean mix generally avoided for load-bearing masonry in wet conditions?

  1. It sets too rapidly to be placed
  2. It makes the mortar too costly
  3. It causes the sand to shrink excessively
  4. It gives lower strength and poor water tightness Correct answer.

Explanation

A 1:6 cement-sand mortar has a low cement content, so the hardened mortar develops lower compressive strength and is more permeable, which is unsuitable where damp resistance and load carrying are needed. Richer mixes such as 1:3 or 1:4 are specified for such situations. Cost and setting time are not the governing reasons here.

Question 10Introduction to Civil Engineering and Engineering Materials

During the initial setting of ordinary Portland cement, the setting time is measured to ensure that the cement:

  1. Does not stiffen too quickly before it can be placed and finished Correct answer.
  2. Contains no unburnt lime
  3. Attains its full design strength within 24 hours
  4. Has a uniform grey colour

Explanation

The initial setting time, which must be not less than 30 minutes for ordinary Portland cement, ensures the paste remains workable long enough for mixing, transport and placing. Final setting time, not initial, controls when hardening is essentially complete, and colour or free lime content are separate tests.

Question 11Introduction to Civil Engineering and Engineering Materials

Which test on coarse aggregate measures its resistance to gradual wear and gives an indication of its suitability for road and pavement work?

  1. Los Angeles abrasion test Correct answer.
  2. Slump test
  3. Vicat test
  4. Sieve analysis

Explanation

The Los Angeles abrasion test tumbles the aggregate with steel balls in a rotating drum and expresses the loss as a percentage, indicating resistance to wear and impact, which matters for pavement aggregates. The slump test measures concrete workability, the Vicat test measures cement setting time, and sieve analysis gives grading.

Question 12Introduction to Civil Engineering and Engineering Materials

In a survey, a reduced level of 100.000 m is known at a benchmark. A backsight of 1.450 m is taken on it and a foresight of 2.150 m on a new point. What is the reduced level of the new point?

  1. 100.700 m
  2. 98.850 m
  3. 99.300 m Correct answer.
  4. 101.300 m

Explanation

The height of instrument equals the benchmark level plus the backsight, that is 100.000 + 1.450 = 101.450 m. The new reduced level is the height of instrument minus the foresight, giving 101.450 − 2.150 = 99.300 m. The point is lower than the benchmark because the foresight is greater than the backsight.

Question 13Introduction to Civil Engineering and Engineering Materials

Which of the following best explains why reinforcement bars are embedded in concrete in reinforced cement concrete members?

  1. Concrete is strong in compression but weak in tension, and steel resists the tension Correct answer.
  2. Concrete is strong in tension and steel adds compressive strength
  3. Steel reduces the weight of the concrete member
  4. Steel prevents the concrete from setting too quickly

Explanation

Plain concrete has good compressive strength but very low tensile strength, so tensile zones of a member would crack. Steel bars have high tensile strength and bond with concrete, so they are placed in tension zones to carry those forces, forming a composite material. Steel does not reduce member weight or control setting.

Question 14Introduction to Civil Engineering and Engineering Materials

A stone sample absorbs 25 g of water when its dry mass is 500 g. What is its percentage water absorption?

  1. 2.5 per cent
  2. 12.5 per cent
  3. 20.0 per cent
  4. 5.0 per cent Correct answer.

Explanation

Water absorption is expressed as the mass of water absorbed divided by the oven-dry mass of the sample, multiplied by 100. Here 25 / 500 × 100 gives 5.0 per cent, which is a low value and indicates a reasonably dense stone suitable for building work.

Question 15Introduction to Civil Engineering and Engineering Materials

Which property of bitumen makes it suitable as a binder in flexible road pavements?

  1. It is a crystalline material with high compressive strength
  2. It is a good conductor of heat and electricity
  3. It sets by hydration when water is added
  4. It is thermoplastic and becomes soft on heating and hard on cooling Correct answer.

Explanation

Bitumen is thermoplastic: it softens when heated so it can coat and bind aggregates during mixing, and hardens on cooling to give a flexible, water-resistant pavement layer. It does not set by hydration like cement, is not crystalline, and is not used for conduction.

Question 16Introduction to Civil Engineering and Engineering Materials

In a brick masonry wall, why are bricks laid in a bond such as English bond with alternate courses of headers and stretchers?

  1. To make the wall lighter in weight
  2. To avoid continuous vertical joints and distribute load across the wall Correct answer.
  3. To allow the wall to be dismantled easily
  4. To reduce the quantity of mortar used in the wall

Explanation

Bonding arranges bricks so that vertical joints in one course are covered by bricks in the course above, preventing continuous vertical joints that would weaken the wall. This breaks the wall into a monolithic mass and distributes loads evenly, improving strength and stability. Economy of mortar and ease of dismantling are not the purposes of bonding.

Question 17Introduction to Civil Engineering and Engineering Materials

Which of the following is classified as a test for the workability of fresh concrete?

  1. Initial setting time test
  2. Soundness test
  3. Compaction factor test Correct answer.
  4. Cube compressive strength test

Explanation

The compaction factor test measures the ease with which fresh concrete can be compacted and is a standard workability test, along with the slump and vee-bee tests. Cube strength is a hardened concrete test, while setting time and soundness are tests performed on cement.

Question 18Introduction to Civil Engineering and Engineering Materials

A lime used in mortar is described as hydraulic lime. What does this mean?

  1. It is slaked with sea water before use
  2. It sets and hardens under water because of the presence of clayey impurities Correct answer.
  3. It is produced by burning pure limestone with no impurities
  4. It is mixed with gypsum to retard setting

Explanation

Hydraulic lime is produced from limestone containing clayey and siliceous impurities, which on burning form compounds that harden even in the presence of water. Fat lime, from nearly pure limestone, hardens mainly by absorbing carbon dioxide from air and cannot set under water. Sea water slaking and gypsum addition are not the defining features.

Question 19Introduction to Civil Engineering and Engineering Materials

Which of the following is the most appropriate reason for providing a foundation wider at the base than the wall it supports?

  1. To reduce the quantity of concrete used
  2. To raise the floor level above the ground
  3. To reduce the pressure on the soil to a value the soil can safely bear Correct answer.
  4. To prevent the entry of rainwater into the building

Explanation

The load of the structure is transmitted to the soil through the foundation, and spreading the base over a larger area reduces the contact pressure so that it does not exceed the safe bearing capacity of the soil. This prevents excessive settlement and shear failure. Raising floor level and excluding rainwater are functions of the plinth and damp-proofing, not of widening the base.

Question 20Introduction to Civil Engineering and Engineering Materials

A concrete mix has a water-cement ratio of 0.50. If 300 kg of cement is used per cubic metre, what is the quantity of water required per cubic metre?

  1. 600 kg
  2. 75 kg
  3. 150 kg Correct answer.
  4. 300 kg

Explanation

The water-cement ratio is the mass of water divided by the mass of cement, so water equals the ratio multiplied by the cement content. Here 0.50 × 300 kg gives 150 kg of water per cubic metre, which is a typical value for normal concrete work.

Question 21Introduction to Civil Engineering and Engineering Materials

A simply supported beam of rectangular section 200 mm wide and 400 mm deep is subjected to a bending moment of 12 kN m. What is the maximum bending stress developed?

  1. 9.00 N/mm²
  2. 1.13 N/mm²
  3. 2.25 N/mm² Correct answer.
  4. 4.50 N/mm²

Explanation

For a rectangular section the section modulus is bd²/6, so here 200 × 400² / 6 = 5.333 × 10⁶ mm³. Bending stress equals moment divided by section modulus, giving 12 × 10⁶ N mm / 5.333 × 10⁶ mm³ = 2.25 N/mm². The result is independent of the span and depends only on the moment and the section.

Question 22Introduction to Civil Engineering and Engineering Materials

Why is a slump test result of 25 mm considered unsuitable for a heavily reinforced concrete column, and what does the value indicate?

  1. It indicates a stiff, low-workability mix that may not fill narrow gaps around dense reinforcement Correct answer.
  2. It indicates segregation of coarse aggregate from the paste
  3. It indicates that the cement has false set
  4. It indicates a very wet mix that will bleed excessively

Explanation

A slump of about 25 mm represents a stiff mix with low workability, which is difficult to place and compact in congested reinforcement, risking voids and honeycombing. Heavily reinforced sections need higher workability, often achieved with admixtures or higher slump, while very wet mixes and segregation correspond to larger slumps or visible separation.

Question 23Introduction to Civil Engineering and Engineering Materials

A soil sample has a natural water content of 20 per cent and a dry density of 1.60 g/cm³. What is its bulk (wet) density?

  1. 2.00 g/cm³
  2. 1.92 g/cm³ Correct answer.
  3. 1.33 g/cm³
  4. 1.80 g/cm³

Explanation

Bulk density equals dry density multiplied by (1 + water content expressed as a decimal), since the water adds mass without changing the soil solids. Here 1.60 × 1.20 = 1.92 g/cm³. The relationship is used in compaction control and earthwork calculations.

Question 24Introduction to Civil Engineering and Engineering Materials

In a theodolite traverse, the sum of the observed interior angles of a closed five-sided polygon is found to be 539°58′. What is the angular error of closure and its likely cause?

  1. An error of 0°02′ due to observational inaccuracy within permissible limits Correct answer.
  2. An error of 0°02′ that must be caused by a faulty instrument only
  3. An error of 0°30′ indicating the wrong number of sides
  4. An error of 1°00′ indicating a gross mistake in one angle

Explanation

The theoretical sum of interior angles of a closed polygon with n sides is (2n − 4) × 90°, which for five sides equals 540°. The observed sum of 539°58′ is short by 0°02′, a small closing error attributable to permissible observational inaccuracies, which is then distributed among the angles. Gross errors or instrument faults would produce much larger discrepancies.

Question 25Surveying and Levelling

In chain surveying, which of the following is classified as a survey station that is selected on the boundary line of the survey area?

  1. Base station
  2. Subsidiary station
  3. Main station Correct answer.
  4. Tie station

Explanation

Main stations are the primary stations selected on the boundary line of the area to be surveyed, and the lines joining them form the framework of the survey. Subsidiary stations lie inside or outside this framework, and tie stations are a special type of subsidiary station on a main line.

Question 26Surveying and Levelling

The principle of surveying that states 'work from the whole to the part' is applied mainly to

  1. increase the number of field readings
  2. avoid the use of check lines
  3. eliminate the need for a base line
  4. reduce the accumulation of errors Correct answer.

Explanation

Working from the whole to the part means establishing a precise, large control framework first and then filling in details within it. Any small errors in the detail work then remain localised instead of accumulating across the entire survey.

Question 27Surveying and Levelling

A chain is tested against a standard length and found to be 20.05 m instead of 20 m. If a line measured with this chain reads 100 m, the true length of the line is

  1. 99.95 m
  2. 100.05 m
  3. 100.25 m Correct answer.
  4. 99.75 m

Explanation

The correction for a chain that is too long is applied by the ratio of true chain length to nominal chain length: true length = measured length × (20.05/20). This gives 100 × 1.0025 = 100.25 m, since the too-long chain records less than the actual distance.

Question 28Surveying and Levelling

In compass surveying, the magnetic bearing of a line is 60° and the magnetic declination is 5° east. The true bearing of the line is

  1. 55°
  2. 70°
  3. 65° Correct answer.
  4. 60°

Explanation

True bearing equals magnetic bearing plus easterly declination, because the magnetic north lies to the east of true north. Hence 60° + 5° = 65°.

Question 29Surveying and Levelling

Which instrument is used to measure the horizontal angle between two objects with high precision by means of a graduated circle read with a micrometer microscope?

  1. Vernier theodolite Correct answer.
  2. Dumpy level
  3. Plane table
  4. Prismatic compass

Explanation

A vernier theodolite carries a horizontal graduated circle read through verniers with micrometer or optical microscopes, allowing precise horizontal and vertical angle measurement. A compass gives only magnetic bearings, a level gives elevations, and a plane table plots graphically.

Question 30Surveying and Levelling

In levelling, the line of collimation is defined as the

  1. vertical line through the staff
  2. line joining two consecutive staff stations
  3. line of sight when the bubble is central Correct answer.
  4. horizontal line through the instrument axis

Explanation

The line of collimation is the line of sight obtained when the bubble is exactly at the centre of its run, i.e. the axis of the telescope in its levelled position. It is the reference line from which staff readings are taken.

Question 31Surveying and Levelling

The reduced level of a point is 50.000 m. A back sight of 1.500 m is taken on it and a foresight of 2.200 m on a forward point. The reduced level of the forward point by the height of instrument method is

  1. 51.500 m
  2. 50.700 m
  3. 49.300 m Correct answer.
  4. 48.800 m

Explanation

Height of instrument = 50.000 + 1.500 = 51.500 m. Reduced level of forward point = HI − foresight = 51.500 − 2.200 = 49.300 m.

Question 32Surveying and Levelling

Which of the following is a temporary adjustment of a dumpy level?

  1. Adjustment of the bubble tube axis
  2. Adjustment of the line of collimation
  3. Adjustment of the cross hairs
  4. Setting up, levelling and focusing Correct answer.

Explanation

Temporary adjustments are made at every setup and include setting up the instrument, levelling it with the foot screws, and focusing the eyepiece and objective. Permanent adjustments such as cross-hair, bubble-tube and collimation adjustments are made only occasionally.

Question 33Surveying and Levelling

In a plane table survey, the method in which the table is set up at one station only and rays are drawn from that station to all visible objects is called

  1. resection
  2. traversing
  3. intersection
  4. radiation Correct answer.

Explanation

In the radiation method the plane table is set up at a single station and rays are drawn towards all objects, distances being scaled along the rays. Intersection uses two stations, traversing uses a series of stations, and resection locates the table station itself.

Question 34Surveying and Levelling

In a closed traverse, the sum of the interior angles of a polygon with n sides should be

  1. (2n − 4) × 90° Correct answer.
  2. (n − 2) × 180°
  3. (2n + 4) × 90°
  4. (n + 2) × 180°

Explanation

The theoretical sum of interior angles of a closed polygon is (2n − 4) × 90°, which is identical to (n − 2) × 180°. Any difference between the observed sum and this value is the angular error of the traverse.

Question 35Surveying and Levelling

Which of the following errors in chain surveying is a cumulative error?

  1. Erroneous marking of the chain end Correct answer.
  2. Variation in temperature
  3. Incorrect ranging
  4. Careless holding of the chain

Explanation

Cumulative errors occur in the same direction and add up over the length of the survey, such as when the chain end is marked wrongly each time. Temperature variation, ranging and careless holding produce errors that may partly cancel and are not necessarily cumulative.

Question 36Surveying and Levelling

The magnetic needle of a prismatic compass is kept short and light mainly to

  1. make the graduations easier to read
  2. increase the magnetic moment greatly
  3. allow the needle to dip in the vertical plane
  4. reduce oscillation and settle quickly Correct answer.

Explanation

A short, light needle has a small moment of inertia, so it comes to rest quickly after the compass is disturbed. This reduces the time spent waiting before each bearing is read.

Question 37Surveying and Levelling

The least count of a vernier theodolite whose main circle is graduated to 20 minutes and whose vernier has 60 divisions is

  1. 30 seconds
  2. 10 seconds
  3. 20 seconds Correct answer.
  4. 1 minute

Explanation

Least count = value of one main-scale division divided by the number of vernier divisions = 20′/60 = 20″. This is the smallest angle that can be read directly on the vernier.

Question 38Surveying and Levelling

In the rise and fall method of reducing levels, a check is applied by comparing the sum of the rises and falls with the

  1. sum of all staff readings
  2. difference between the first and last reduced levels Correct answer.
  3. height of the instrument at the last station
  4. product of the number of setups and the least count

Explanation

In the rise and fall method, the algebraic sum of rises minus falls must equal the difference between the first and the last reduced levels. This arithmetic check verifies the reduction work.

Question 39Surveying and Levelling

A staff reading taken on a point whose reduced level is required is 1.250 m, and the height of instrument is 100.000 m. The reduced level of the point is

  1. 100.000 m
  2. 98.750 m Correct answer.
  3. 101.250 m
  4. 99.875 m

Explanation

Reduced level = height of instrument − staff reading = 100.000 − 1.250 = 98.750 m. A positive staff reading always lowers the RL below the instrument height.

Question 40Surveying and Levelling

The operation of bringing the vertical axis of a theodolite exactly vertical before taking observations is known as

  1. focusing of the telescope
  2. centring of the theodolite
  3. levelling of the theodolite Correct answer.
  4. transiting of the telescope

Explanation

Levelling the theodolite means adjusting the foot screws until the plate bubble is central, making the vertical axis truly vertical. Centring aligns the instrument over the station mark, focusing sharpens the image, and transiting reverses the telescope.

Question 41Surveying and Levelling

In a compass traverse, local attraction is detected by

  1. observing the dip of the needle
  2. checking the closing error of the traverse
  3. measuring the length of each line twice
  4. comparing fore and back bearings of each line Correct answer.

Explanation

Local attraction at a station deflects the needle, so the fore and back bearings of a line differ by exactly 180° only when both stations are free from it. A discrepancy between fore and back bearings therefore reveals the presence of local attraction.

Question 42Surveying and Levelling

The main purpose of a cross staff in chain surveying is to

  1. set out lines at right angles to a chain line Correct answer.
  2. level the chain line over undulating ground
  3. determine the magnetic bearing of a line
  4. measure horizontal angles to one minute

Explanation

A cross staff is a simple instrument used to erect or set out perpendiculars to a chain line at a given point. It is used for offsets and is not intended for precise angular measurement.

Question 43Surveying and Levelling

The distance between two points measured along a slope is 50 m and the vertical difference in level between them is 30 m. The horizontal distance between the points is

  1. 35 m
  2. 20 m
  3. 40 m Correct answer.
  4. 45 m

Explanation

By Pythagoras, horizontal distance = √(50² − 30²) = √(2500 − 900) = √1600 = 40 m. The slope distance is the hypotenuse and the level difference is the vertical leg.

Question 44Surveying and Levelling

A contour line on a topographic map is best described as a line joining points of

  1. equal elevation Correct answer.
  2. equal magnetic bearing
  3. equal slope angle
  4. equal horizontal distance from a station

Explanation

A contour is the locus of points having the same reduced level, so it represents a constant elevation on the ground. The spacing of contours indicates the steepness of the terrain.

Question 45Surveying and Levelling

In levelling, the curvature of the earth causes the staff reading to be

  1. too small, requiring a positive correction
  2. unaffected, since the bubble is central
  3. too great, requiring a positive correction
  4. too great, requiring a negative correction Correct answer.

Explanation

Because of the earth's curvature, the line of sight rises above the level surface, so the staff appears to read higher than the true value. The correction for curvature is therefore negative and equals approximately 0.0785 d² metres for distance d in kilometres.

Question 46Surveying and Levelling

The base line in a chain survey should preferably be

  1. the longest line passing through the centre of the area Correct answer.
  2. any subsidiary line joining two tie stations
  3. the shortest line along one boundary
  4. a line parallel to the longest boundary

Explanation

A long base line through the middle of the area gives a strong framework and reduces the relative error of the survey. Shorter lines and boundary lines are used as check or tie lines instead.

Question 47Surveying and Levelling

The total station differs from a conventional theodolite mainly because it

  1. requires a plane table for plotting
  2. measures distance electronically along with angles and stores the data Correct answer.
  3. measures only vertical angles
  4. uses a magnetic needle to obtain bearings

Explanation

A total station combines an electronic theodolite with an electronic distance measuring unit and an onboard processor, so it records angles and distances and can compute coordinates directly. A conventional theodolite measures angles only.

Question 48Surveying and Levelling

A level was set up midway between two points A and B, and the staff readings were 1.500 m at A and 1.200 m at B. If the instrument is later moved and set up near A, the difference in level between A and B

  1. remains unchanged, so the result is free from collimation error Correct answer.
  2. increases because the instrument is nearer A
  3. becomes zero
  4. decreases because the sight to B is longer

Explanation

When the instrument is exactly midway between the two staff stations, the collimation error affects both sights equally and cancels out. The true difference in level is therefore obtained regardless of any residual collimation error.

Question 49Surveying and Levelling

In a theodolite, the vertical circle is used to measure

  1. horizontal angles between stations
  2. angles of elevation and depression Correct answer.
  3. magnetic bearings of lines
  4. the length of a base line

Explanation

The vertical circle of a theodolite gives the angle of elevation or depression of the line of sight with respect to the horizontal. These angles are used to compute heights and distances in trigonometric levelling.

Question 50Surveying and Levelling

In a chain survey, the frame of a chain is made of a metal that is soft and ductile so that it can be bent for repair without breaking. Which metal is normally used for the links of a metric chain?

  1. High carbon steel
  2. Aluminium
  3. Mild steel Correct answer.
  4. Cast iron

Explanation

Chain links are made from mild steel wire because it is soft, ductile and can be bent or straightened during repair without cracking. Cast iron is brittle and would snap when a link is opened for adjustment, while hard grades resist the bending needed for joint work. Aluminium is light but too soft and weak for a chain that is dragged over ground.