DRDO STA Computer Science Civil Tier 2 Mock Test- 5 Free Online Test 2026

Some pigments are toxic, such as those used in lead paint. Paint manufacturers replaced lead white with a less toxic substitute, which can even be used to colour food titanium white (titanium dioxide).

where

e = void ratio

D = effective size of soil particle

γ = weight density of fluid

μ = viscosity of fluid

c = constant (depends upon the shape of the particle)

∴ The coefficient of permeability depends upon the shape of particles, the diameter of particles, and void ratio.

Distance between A & B

= 100 + 66 = 166 ft

In a balanced section, an increase in the area of steel will result in higher tensile stress carrying capacity.

To counteract or generate equivalent compressive stress/force, the neutral axis has to come down.

In a singly reinforced rectangular beam section,

implies that

x_u∝A_st

which means as the percentage area of tensile steel increases the depth of the neutral axis increases

The pressure measured above the absolute zero or complete vacuum is called absolute pressure.
Absolute pressure = Gauge pressure + Local atmosphere pressure.
also Absolute pressure = Local atmosphere pressure - Negative gauge pressure.

For 20 m chain length,

The degree of curve (D) is given by ⇒ D=1146/R

For 30 m chain length,

Degree of curve (D) is given by ⇒ D=1729/R

Calculation:

∴ For 20 m chain length, D = 1146/229.2 = 5°

∴ For 30 m chain length, D = 1729/229.2 = 7.54°

∴ Most appropriate option is 5° and hence 20 m chain length should be considered.

Lead nitrate is a destructive impurity in mixing water. Its effects can include:

• Toxicity: Lead is a harmful substance that can poison humans and animals.
• Corrosion: It can cause corrosion of metals and deterioration of concrete.
• Adverse reactions: Lead nitrate may react negatively with other materials, affecting structural integrity.

In contrast, other impurities like calcium chloride, alkalies, and algae may have lesser or different impacts, but they are not as destructive as lead nitrate.

It is generally employed to excavate trenches, pits for basements and generally for grading work, which requires precise control of depths.

Total float affects both preceding and succeeding activities.
Free float affects only succeeding activities.

The gross amount of water to be applied to the field will be

G|R = 8cm/0.75= 10.67 cm

The initial setting time of concrete is affected by temperature. At different temperatures, the behaviour of concrete changes significantly.

• At temperatures below 0°C, concrete can freeze, which slows down the setting process considerably.
• Specifically, at -10°C, the setting time is extremely prolonged, making it difficult for the concrete to gain strength.
• At -4°C, concrete still experiences a significant delay in setting.
• At 0°C, concrete can begin to set, but this occurs much slower than at warmer temperatures.
• At 4°C, the setting time improves, but it is still slower than at higher temperatures.

In summary, the initial setting time of concrete is notably affected by cold temperatures, with 0°C being the threshold where it can start to set effectively, although still at a slower rate.

Head loss for well rounded entrance as compared to sharp cornered entrance is very small.

1. Helps in planning efficient time schedule:

   • The critical path method (CPM) is used to identify the longest sequence of tasks in a project that must be completed on time for the project to be finished by its deadline. Knowing the critical path helps in planning an efficient time schedule by focusing on these critical tasks.

2. Indicates the shortest path in time:

   • This statement is incorrect. The critical path actually represents the longest path through the project, not the shortest. It determines the minimum project duration by identifying the sequence of dependent tasks that have the longest total duration.

3. Helps in crashing the project judiciously:

   • Crashing a project involves adding resources to critical path tasks to complete them more quickly, thus reducing the project duration. Identifying the critical path is crucial for effective crashing, as only tasks on the critical path will affect the overall project completion time.

4. Helps in encouraging discipline in execution:

   • By highlighting the tasks that cannot be delayed without affecting the project completion date, the critical path helps enforce discipline in execution. Project managers and team members can focus their attention on critical tasks to ensure they stay on track.

Therefore, the correct answer is: 1, 3 and 4

Here e_x, e_y, and e_z are the strain in the x, y, and z directions, respectively.

Imhoff tank: It is a robust and effective settler that causes a suspended solids reduction of 50 to 70%, COD reduction of 25 to 50%, and leads to potentially good sludge stabilization.

It consists of two compartments:

Upper Compartment: This compartment has a circular or rectangular shape with V-shaped walls and a slot at the bottom, allowing solids to settle into the digestion compartment, while preventing foul gas from rising up and disturbing the settling process. It is exposed to atmosphere, and thus working condition is aerobic.

Lower Compartment: In this compartment, sludge accumulates and is compacted and partially stabilized through anaerobic digestion. Thus, working condition is anaerobic

Basic capacity: The basic capacity is the maximum numbers of passenger cars that can pass a given point on a lane or a roadway during one hour under the most ideal roadway and traffic conditions that can possibly be attained.

Possible capacity: It is the maximum number of vehicles that can pass a given point on a lane or roadway during one hour under the prevailing roadway and traffic conditions.

Practical Capacity: It is the maximum number of vehicles that can pass a given point on a lane or roadway during one hour with creating unreasonable delay under the prevailing roadway and traffic conditions.

Design capacity: it is the practical capacity or a smaller value determined for use in designing the highway to accommodate the design hourly volume.

Theoretical Capacity: It is the number of vehicles passing any point in one hour per lane.

Workability of concrete can be tested by:

1. Slump Test

2. Compaction factor test

3. Vee-Bee test

1. Adjustment of Vertical cross hair: The vertical cross hair should lie in a plane perpendicular to the horizontal a×is.

2. Adjustment of plate level a×es: The a×is of each plate level should lie in a plane perpendicular to the vertical a×is.

3. Adjustment of line of sight: In a properly adjusted instrument, the line of sight is perpendicular to the horizontal a×is.

4. Adjustment of horizontal a×is: The horizontal a×is is required to be perpendicular to the vertical a×is.

5. Adjustment of the a×is of the telescope

6. Adjustment of vertical circle inde×: The object of this adjustment is to set the vertical circle to zero when the line of sight is horizontal and the altitude bubble is centered.

Advantages of a flat-footed rail are as followed:

i) No chair is required as rails are directly spiked to the sleepers.

ii) It is stiffer vertically as well as laterally.

iii) It is less liable to kinks development.

iv) It is economical than all other types of rail.

v) It distributes the load over a larger area of the sleeper.

1. The water/powder ratio by volume is to be 0.80 to 1.00

2. Total powder content to be 160 to 240 liters (400-600 kg) per m3

3. The sand content may be more than 38% of the mortar volume.

4. Coarse aggregate content should normally be 28 to 35% volume of the mix.

5. The water/cement ratio is selected based on the strength required. In any case, water content should not exceed 200 liters/m3.

6. The volume of aggregates in total would form 50 to 60% of the volume of concrete.