NEET Physics PYQ 2025 — Set 2 (Questions 11–20) — Solved (English + Hindi)
Continuation of the NEET PYQ series. Ten original NEET-style questions with concise solutions in English followed by Hindi (Hinglish) notes.
Q11. Escape velocity from a planet of radius \(R\) and mass \(M\) is \(v_e\). If the planet's density remains constant but its radius doubles, the new escape velocity is proportional to:
(Gravitation)
Answer — (d) \(v_e/\sqrt{2}\)
English: Escape velocity \(v_e=\sqrt{2GM/R}\). For constant density \(\rho \propto M/R^3\) ⇒ \(M\propto R^3\). If \(R\to2R\), \(M\to8M\). New \(v'_e=\sqrt{2G(8M)/(2R)}=\sqrt{8/2}\sqrt{2GM/R}=\sqrt{4}v_e=2v_e\). Wait—careful: using base values relative scaling gives \(v'_e= \sqrt{ \dfrac{2G(8M)}{2R} } = \sqrt{8/2}\,v_e = 2v_e\). So correct is (c) \(2v_e\).
Hindi (Hinglish): Density constant hone par \(M\propto R^3\). Agar R double hua toh M 8 guna hota hai. Substitute karne par \(v'_e=2v_e\). (विकल्प c)।
Q12. The slope of a velocity–time graph gives:
(Kinematics)
Answer — (c) Acceleration
English: Slope = \(dv/dt\) = acceleration.
Hindi (Hinglish): v–t graph ka slope acceleration deta hai. (विकल्प c)।
Q13. Energy stored in an inductor of inductance \(L\) carrying current \(I\) is:
(Electromagnetism)
Answer — (b) \(\dfrac12 LI^2\)
English: Work done to build current = \( \int_0^I L i \, di = \tfrac12 LI^2\).
Hindi (Hinglish): Inductor mein energy \(=1/2\,LI^2\). (विकल्प b)।
Q14. Drift velocity of electrons in a wire is inversely proportional to:
(Current Electricity)
Answer — (b) Cross-sectional area
English: Drift velocity \(v_d = I/(nAe)\) ⇒ \(v_d \propto 1/A\) (for fixed I, n, e).
Hindi (Hinglish): Drift velocity wire area ke inverse hoti hai. (विकल्प b)।
Q15. Magnetic field inside a long solenoid of n turns per meter carrying current I is:
(Magnetism)
Answer — (a) \(\mu_0 n I\)
English: Using Ampère's law for ideal long solenoid: \(B=\mu_0 n I\).
Hindi (Hinglish): Long solenoid mein B = μ₀ n I. (विकल्प a)।
Q16. Radius of electron path in perpendicular magnetic field B (speed v, charge e, mass m) is:
(Circular motion in B)
Answer — (a) \(\dfrac{mv}{eB}\)
English: Centripetal force \(mv^2/r = evB\) ⇒ \(r=mv/(eB)\).
Hindi (Hinglish): Equation se r = mv/(eB) milta hai. (विकल्प a)।
Q17. Momentum of a photon of frequency \(\nu\) is:
(Photon properties)
Answer — (a) \(\dfrac{h\nu}{c}\)
English: Photon energy \(E=h\nu\), momentum \(p=E/c = h\nu/c\).
Hindi (Hinglish): Photon ka momentum p = hν/c. (विकल्प a)।
Q18. Which nucleus has the highest binding energy per nucleon?
(Nuclear Physics)
Answer — (b) Iron-56
English: Binding energy per nucleon peaks around iron/nickel (Fe-56) making them most stable nuclei.
Hindi (Hinglish): Fe-56 jaise nuclei maximum binding energy per nucleon rakhte hain. (विकल्प b)।
Q19. Half-life of a radioactive isotope depends on:
(Radioactivity)
Answer — (c) Nuclear structure (intrinsic)
English: Radioactive decay is nuclear and random; half-life is intrinsic property not affected by normal external conditions.
Hindi (Hinglish): Half-life nucleus ki intrinsic property hai; aam external conditions se change nahi hoti. (विकल्प c)।
Q20. Modulation in communication primarily helps to:
(Waves & Communication)
Answer — (b) Allow transmission over long distances & multiplexing
English: Modulation shifts baseband to carrier for efficient propagation, frequency allocation and multiplexing.
Hindi (Hinglish): Modulation se signal ko carrier par bheja jata hai — long distance aur multiplexing possible hota hai. (विकल्प b)।
Next: Set 3 (Q21–Q30)
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