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Friday, 9 October

NEET UG 2025 · Physics · Question 24

NEET 2025 Physics, question 24

Question 24 of the NEET 2025 paper (code 45) is a Physics question from Mechanical Properties of Fluids. Its idea, Speed of Efflux, was asked twice, in 2019 and 2025, across NEET 2017–2026. The NTA final answer key gives option 3.

Updated 2026-10-08

Q24 · Physics

A balloon is made of a material of surface tension SS and its inflation outlet (from where gas is filled in it) has small area AA. It is filled with a gas of density ρ\rho and takes a spherical shape of radius RR. When the gas is allowed to flow freely out of it, its radius rr changes from RR to 0 (zero) in time TT. If the speed v(r)v(r) of gas coming out of the balloon depends on rr as rar^a and T∝SαAβργRδT \propto S^\alpha A^\beta \rho^\gamma R^\delta then

  1. 1a=12,α=12,β=−1,γ=+1,δ=32a = \frac{1}{2}, \alpha = \frac{1}{2}, \beta = -1, \gamma = +1, \delta = \frac{3}{2}
  2. 2a=−12,α=−12,β=−1,γ=−12,δ=52a = -\frac{1}{2}, \alpha = -\frac{1}{2}, \beta = -1, \gamma = -\frac{1}{2}, \delta = \frac{5}{2}
  3. 3a=−12,α=−12,β=−1,γ=12,δ=72a = -\frac{1}{2}, \alpha = -\frac{1}{2}, \beta = -1, \gamma = \frac{1}{2}, \delta = \frac{7}{2}Official answer
  4. 4a=12,α=12,β=−12,γ=12,δ=72a = \frac{1}{2}, \alpha = \frac{1}{2}, \beta = -\frac{1}{2}, \gamma = \frac{1}{2}, \delta = \frac{7}{2}

Official answer: option 3 · NTA final answer key

Same idea

Speed of Efflux, in other papers

NEET asked this idea twice, in 2019 and 2025. The other question below.

  • 2019 Q38A small hole of area of cross-section 2 mm² is present near the bottom of a fully filled open tank of height 2 m. Taking g=10g = 10 m/s²,…Numerical · Medium

Speed of Efflux: every question and how it was framed

The chapter

Mechanical Properties of Fluids in ten years of NEET

15 questions from 2017–2026, asked in 10 of 10 papers, about 1.4 a paper. Fluid Statics and Dynamics alone had 5.

Chapter analysisStudy this chapterPractise this chapter

Mechanical Properties of Fluids: questions per paper

0241’171’182’191’201’212’222’231’242’252’26