GATE Practice Set 6

15 Q · 15 min · Solved with answers
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Sections: General AptitudeCore SubjectEngineering Mathematics
Q1.
The number of input lines for 3-to-8 decoder is:
A. 8
B. 2
C. 3
D. 4
Correct Answer: C
3-to-8 decoder: 3 inputs, 8 outputs.
Q2.
What is the time complexity of binary search on a sorted array of n elements?
A. O(n)
B. O(log n)
C. O(n^2)
D. O(n log n)
Correct Answer: B
Binary search divides the search space in half each iteration, giving O(log n) time complexity.
Q3.
In an isothermal process, which quantity remains constant?
A. Pressure
B. Volume
C. Temperature
D. Entropy
Correct Answer: C
Isothermal: T = constant, PV = constant (for ideal gas).
Q4. Engineering Mathematics
What is the determinant of the matrix [1, 2; 3, 4]?
A. -2
B. 2
C. -1
D. 1
Correct Answer: A
The determinant of a 2x2 matrix [a, b; c, d] is given by ad - bc. In this case, the determinant is (1)(4) - (2)(3) = 4 - 6 = -2.
Q5.
The bearing capacity of soil is improved by:
A. Water addition
B. Compaction
C. Excavation
D. Aeration
Correct Answer: B
Compaction increases soil density -> higher bearing capacity.
Q6.
The standard penetration test (SPT) N-value indicates:
A. Water content
B. Soil density/strength
C. Permeability
D. Plasticity
Correct Answer: B
SPT N-value correlates with relative density and strength of soil.
Q7. Core Subject
In a control system, what is the purpose of the feedback loop?
A. To increase the gain of the system
B. To decrease the stability of the system
C. To reduce the error between the desired output and the actual output
D. To increase the noise in the system
Correct Answer: C
The purpose of the feedback loop in a control system is to reduce the error between the desired output and the actual output by continuously monitoring the output and adjusting the input to minimize the error.
Q8. General Aptitude
A person walks at 5 km/h and runs at 8 km/h. If total time for 13 km is 2 hours, how much did he walk?
A. 5 km
B. 5 km
C. 8 km
D. 3 km
Correct Answer: B
Let walk time = t hr, run time = 2-t. 5t + 8(2-t) = 13 -> t = 1 hr. Walk distance = 5 km.
Q9.
TIG welding uses which electrode?
A. Consumable
B. Non-consumable tungsten
C. Copper
D. Steel
Correct Answer: B
TIG (Tungsten Inert Gas) uses non-consumable tungsten electrode.
Q10.
What does the following C expression evaluate to? (Assume i = 5) i++ + ++i
A. 10
B. 11
C. 12
D. Undefined
Correct Answer: C
i++ uses current value (5) then increments to 6. ++i increments to 7 then uses 7. So 5 + 7 = 12.
Q11.
An ideal op-amp has infinite:
A. Output impedance
B. Input impedance
C. Bandwidth
D. Both B and C
Correct Answer: B
Ideal op-amp: infinite input impedance, zero output impedance, infinite gain.
Q12.
Poisson's ratio for most metals is about:
A. 0.1
B. 0.3
C. 0.5
D. 1.0
Correct Answer: B
Poisson's ratio for metals: 0.25-0.35 (steel ~0.3). 0.5 for incompressible.
Q13.
In orthogonal cutting, the cutting edge is:
A. Parallel to work surface
B. Perpendicular to cutting velocity
C. At 45 degrees
D. Inclined
Correct Answer: B
Orthogonal cutting: cutting edge to cutting velocity direction.
Q14.
Thevenin's theorem is used to simplify:
A. Non-linear circuits
B. Linear circuits
C. Digital circuits
D. Magnetic circuits
Correct Answer: B
Thevenin's theorem applies to linear circuits (voltage source + series resistance).
Q15.
The worst-case time complexity of quicksort is:
A. O(log n)
B. O(n log n)
C. O(n^2)
D. O(n)
Correct Answer: C
Quicksort worst-case O(n^2) when pivot is smallest/largest element (e.g., sorted array with naive pivot).