KCET 2023 previous year paper practice · PYQ-pattern set

KCET 2023 PYQ-pattern questions

Showing 10 of the 20 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 · Units and Measurement (1st PUC)

   The percentage error in the measurement of mass and speed are 2% and 3% respectively. The maximum percentage error in the calculation of kinetic energy is:

   • A. 5%
   • B. 8%
   • C. 10%
   • D. 12%
   Answer and solution

   Answer: B

   Kinetic energy KE = ½mv². The percentage error in KE is given by ΔKE/KE = Δm/m + 2(Δv/v) = 2% + 2(3%) = 2% + 6% = 8%.

2. Q2 · System of Particles and Rotational Motion (1st PUC)

   A disc of radius 0.5 m and mass 2 kg is rotating about an axis passing through its center perpendicular to its plane. If the angular velocity is 4 rad/s, the rotational kinetic energy is:

   • A. 1 J
   • B. 2 J
   • C. 3 J
   • D. 4 J
   Answer and solution

   Answer: B

   Moment of inertia of disc I = ½MR² = ½ × 2 × (0.5)² = 0.25 kg·m². Rotational KE = ½Iω² = ½ × 0.25 × 4² = 0.125 × 16 = 2 J.

3. Q3 · Thermal Properties of Matter (1st PUC)

   Two metal rods A and B of equal length have thermal conductivities in the ratio 2:3 and cross-sectional areas in the ratio 3:4. When their ends are maintained at the same temperature difference, the ratio of heat conducted through A to that through B in the same time is:

   • A. 1:2
   • B. 8:9
   • C. 2:3
   • D. 3:2
   Answer and solution

   Answer: A

   Rate of heat flow Q/t = KA(ΔT)/L. Taking ratio: (Q/t)ₐ/(Q/t)ᵦ = (Kₐ/Kᵦ) × (Aₐ/Aᵦ) = (2/3) × (3/4) = 6/12 = 1/2.

4. Q4 · Electric Charges and Fields (2nd PUC)

   The electric field at a distance of 40 cm from a point charge is 500 N/C. The magnitude of the point charge is approximately: (Take 1/4πε₀ = 9 × 10⁹ N·m²/C²)

   • A. 4.5 × 10⁻⁹ C
   • B. 8.9 × 10⁻⁹ C
   • C. 1.8 × 10⁻⁸ C
   • D. 3.6 × 10⁻⁸ C
   Answer and solution

   Answer: B

   Using E = kq/r², we get q = Er²/k = 500 × (0.4)² / (9 × 10⁹) = 500 × 0.16 / (9 × 10⁹) ≈ 8.9 × 10⁻⁹ C.

5. Q5 · Moving Charges and Magnetism (2nd PUC)

   A straight conductor of length 0.5 m carrying a current of 4 A is placed perpendicular to a uniform magnetic field of 0.8 T. The force experienced by the conductor is

   • A. 1.6 N
   • B. 2.0 N
   • C. 0.8 N
   • D. 3.2 N
   Answer and solution

   Answer: A

   Force on a current-carrying conductor is F = BIL sinθ. Here, F = 0.8 × 4 × 0.5 × sin90° = 1.6 N.

6. Q6 · Ray Optics and Optical Instruments (2nd PUC)

   A convex lens of focal length 20 cm forms an image at a distance of 60 cm from the lens. The object distance is

   • A. 30 cm
   • B. 15 cm
   • C. 40 cm
   • D. 12 cm
   Answer and solution

   Answer: A

   Using lens formula 1/f = 1/v - 1/u, we get 1/20 = 1/60 - 1/u. Solving: 1/u = 1/60 - 1/20 = -2/60, so u = -30 cm.

7. Q7 · Atoms (2nd PUC)

   If the radius of the first Bohr orbit in hydrogen atom is r₀, what is the radius of the third Bohr orbit?

   • A. 3r₀
   • B. 6r₀
   • C. 9r₀
   • D. 27r₀
   Answer and solution

   Answer: C

   According to Bohr's model, the radius of nth orbit rₙ = n²r₀. For n=3, r₃ = 9r₀.

8. Q8 · Structure of Atom (1st PUC)

   How many orbitals are present in the M shell (n=3) of an atom?

   • A. 4
   • B. 9
   • C. 16
   • D. 25
   Answer and solution

   Answer: B

   Number of orbitals in a shell = n². For M shell (n=3), number of orbitals = 3² = 9.

9. Q9 · States of Matter — Gases and Liquids (1st PUC)

   At constant temperature, if the volume of a given mass of gas is halved, the pressure becomes:

   • A. Double
   • B. Half
   • C. Four times
   • D. One-fourth
   Answer and solution

   Answer: A

   According to Boyle's law, at constant temperature P₁V₁ = P₂V₂. If volume is halved, pressure must double to maintain the relationship.

10. Q10 · s-Block Elements (1st PUC)

    Which of the following alkali metals has the lowest melting point?

    • A. Li
    • B. Na
    • C. K
    • D. Cs
    Answer and solution

    Answer: D

    Among alkali metals, melting point decreases down the group due to weaker metallic bonding. Cesium (Cs) has the lowest melting point.