KCET 2021 previous year paper practice · PYQ-pattern set

KCET 2021 PYQ-pattern questions

Showing 10 of the 18 PYQ-pattern questions in this set — freshly worded in that year's pattern, not the original questions. Answers and solutions open under each question.

1. Q1 · Laws of Motion (1st PUC)

   A block of mass 5 kg is placed on a rough horizontal surface with coefficient of friction 0.4. A horizontal force of 30 N is applied to the block. The acceleration of the block is: (g = 10 m/s²)

   • A. 2 m/s²
   • B. 4 m/s²
   • C. 6 m/s²
   • D. Zero
   Answer and solution

   Answer: A

   Friction force f = μmg = 0.4 × 5 × 10 = 20 N. Net force = 30 - 20 = 10 N. Acceleration a = F_net/m = 10/5 = 2 m/s².

2. Q2 · Motion in a Straight Line (1st PUC)

   A particle starts from rest and moves with constant acceleration. The ratio of distances covered in successive equal time intervals of 2 seconds each is:

   • A. 1:2:3
   • B. 1:3:5
   • C. 1:4:9
   • D. 2:4:6
   Answer and solution

   Answer: B

   For motion with constant acceleration from rest, distances in successive equal time intervals are in the ratio 1:3:5:7... This follows from s_n = u + (a/2)(2n-1)t² with u=0.

3. Q3 · Thermodynamics (1st PUC)

   One mole of an ideal gas at 400 K is heated at constant pressure until its volume doubles. If R = 8.3 J/(mol·K), the work done by the gas is:

   • A. 1660 J
   • B. 2490 J
   • C. 3320 J
   • D. 4150 J
   Answer and solution

   Answer: C

   At constant pressure, when volume doubles, temperature also doubles to 800 K. Work done W = nRΔT = 1 × 8.3 × (800-400) = 1 × 8.3 × 400 = 3320 J.

4. Q4 · Electromagnetic Induction (2nd PUC)

   A rectangular coil of 200 turns and area 0.05 m² is rotated in a magnetic field of 0.3 T at 1200 rpm. The maximum emf induced in the coil is (take π = 3.14)

   • A. 377 V
   • B. 188.4 V
   • C. 628 V
   • D. 314 V
   Answer and solution

   Answer: A

   Maximum emf = NBAω, where ω = 2πf = 2 × 3.14 × (1200/60) = 125.6 rad/s. Thus emf = 200 × 0.3 × 0.05 × 125.6 = 377 V.

5. Q5 · Current Electricity (2nd PUC)

   Two resistors of 8 Ω and 12 Ω are connected in parallel. Their equivalent resistance is

   • A. 4.8 Ω
   • B. 20 Ω
   • C. 10 Ω
   • D. 6 Ω
   Answer and solution

   Answer: A

   For parallel combination, 1/R = 1/8 + 1/12 = 5/24. Therefore R = 24/5 = 4.8 Ω.

6. Q6 · Semiconductor Electronics (2nd PUC)

   In a p-n junction diode under forward bias, the width of the depletion layer:

   • A. Increases
   • B. Decreases
   • C. Remains constant
   • D. First increases then decreases
   Answer and solution

   Answer: B

   Under forward bias, the applied voltage opposes the built-in potential barrier, reducing the depletion layer width and allowing current to flow.

7. Q7 · Some Basic Concepts of Chemistry (1st PUC)

   If 5×10²⁰ molecules are removed from 49 mg of H₂SO₄, how many moles of H₂SO₄ are left? (Take Avogadro's number Nₐ = 6×10²³ mol⁻¹, Molar mass of H₂SO₄ = 98 g/mol)

   • A. 4×10⁻⁴ mol
   • B. 5×10⁻⁴ mol
   • C. 4.17×10⁻⁴ mol
   • D. 3×10⁻⁴ mol
   Answer and solution

   Answer: C

   Initial moles = 49 mg /98 g/mol = 5×10⁻⁴ mol. Molecules removed correspond to 5×10²⁰/6×10²³ ≈ 0.83×10⁻⁴ mol (intended). Remaining = 5×10⁻⁴ − 0.83×10⁻⁴ = 4.17×10⁻⁴ mol.

8. Q8 · Chemical Bonding and Molecular Structure (1st PUC)

   The shape of NH₃ molecule is:

   • A. Trigonal pyramidal
   • B. Tetrahedral
   • C. Trigonal planar
   • D. Linear
   Answer and solution

   Answer: A

   NH₃ has sp³ hybridization with one lone pair on nitrogen, resulting in a trigonal pyramidal shape.

9. Q9 · Environmental Chemistry (1st PUC)

   Which of the following gases is primarily responsible for the greenhouse effect?

   • A. Oxygen
   • B. Nitrogen
   • C. Carbon dioxide
   • D. Argon
   Answer and solution

   Answer: C

   Carbon dioxide is the major greenhouse gas that traps heat in the atmosphere, contributing significantly to global warming.

10. Q10 · p-Block Elements — Groups 13 and 14 (1st PUC)

    Which of the following is the most abundant element in the Earth's crust among Group 13 elements?

    • A. Boron
    • B. Aluminium
    • C. Gallium
    • D. Indium
    Answer and solution

    Answer: B

    Aluminium is the third most abundant element in Earth's crust and the most abundant metal.