NEET UG

2,056 solved questions 5 notes 85 tests

Ask a question

A 40 μF capacitor is connected to a 200 V, 50 Hz ac supply. The rms value of the current in the circuit is, nearly : Answer: 3. 2.5 A Capacitive reactance X_C=1/2π fC . X_C=frac12π×50×40×10⁻⁶≈79.6\ Ω I_rms=fracV_rmsX_C=200/79.6≈2.5\ A Answer: option 3. Reactance, impedance, LCR series circuit, resonance 1 answer
The ratio of contributions made by the electric field and magnetic field components to the intensity of an electromagnetic wave is : (c = speed of electromagnetic waves) Answer: 2. 1 : 1 In an electromagnetic wave the energy is shared equally between the electric and magnetic fields. Electric energy density =... EM waves, characteristics and transverse nature 1 answer
Light with an average flux of 20 W/cm^2 falls on a non-reflecting surface at normal incidence having surface area 20 cm^2. The energy received by the surface during time span of 1 minute is : Answer: 3. 24×10³ J Energy received = flux × area × time. E=20\ W/cm²×20\ cm²×60\ s=24000\ J=24×10³\ J Answer: option 3. EM waves, characteristics and transverse nature 1 answer
The increase in the width of the depletion region in a p-n junction diode is due to : Answer: 2. reverse bias only In reverse bias, the applied voltage adds to the barrier. Majority carriers are pulled away from the junction,... p-n junction diode I-V characteristics 1 answer
For transistor action, which of the following statements is correct ? Answer: 4. The base region must be very thin and lightly doped. For transistor action the base must be very thin and lightly doped, so most... Semiconductors 1 answer
A spherical conductor of radius 10 cm has a charge of 3.2×10^-7 C distributed uniformly. What is the magnitude of electric field at a point 15 cm from the centre of the sphere ?≤ft(1/4πε_0 = 9×10^9\ N m^2/C^2) Answer: 2. 1.28×10⁵ N/C Outside a uniformly charged sphere, the field is the same as that of a point charge at the centre. E=1/4πε₀Q/r²=frac... Electric flux and Gauss's law applications 1 answer
In a certain region of space with volume 0.2 m^3, the electric potential is found to be 5 V throughout. The magnitude of electric field in this region is : Answer: 1. zero Electric field is the negative gradient of potential: E=-dV/dx . The potential is constant (5 V) throughout the region, so i... Electric potential, potential difference, equipotential surfaces 1 answer
A screw gauge has least count of 0.01 mm and there are 50 divisions in its circular scale.The pitch of the screw gauge is : Answer: 3. 0.5 mm Least count =pitch/number of circular divisions . pitch=0.01\ mm×50=0.5\ mm Answer: option 3. Vernier calipers and screw gauge 1 answer
A body weighs 72 N on the surface of the earth. What is the gravitational force on it, at a height equal to half the radius of the earth ? Answer: 2. 32 N Gravitational force varies as g , and g at height h is g(R/R+h)² . With h=R/2 : (R/1.5R)²=4/9 . F=72×4/9=32\ N Answer: optio... Acceleration due to gravity and its variation with altitude and depth 1 answer
A cylinder contains hydrogen gas at pressure of 249 kPa and temperature 27^°C.Its density is : (R = 8.3 J mol^-1 K^-1) Answer: 2. 0.2 kg/m ³ Use the ideal gas equation in density form: P=ρ RT/M . M=2×10⁻³ kg/mol, T=300 K, P=2.49×10⁵ Pa. ρ=PM/RT=frac2.49×10⁵×2... Equation of state of a perfect gas, work done on compressing a gas 1 answer
The mean free path for a gas, with molecular diameter d and number density n can be expressed as : Answer: 2. 1/√(2) nπ d² The standard result for the mean free path of a gas is λ=1/sqrt2 nπ d² It falls with number density n (more molecule... Mean free path, Avogadro's number 1 answer
The Brewsters angle i_b for an interface should be : Answer: 3. 45^° < i_b < 90^° Brewster's law: tan i_b=μ , where μ is the relative refractive index of the interface. Since μ>1 for an ordinar... Polarization, Brewster's law, Polaroids 1 answer
A ray is incident at an angle of incidence i on one surface of a small angle prism (with angle of prism A) and emerges normally from the opposite surface. If the refractive index of the material of the prism is μ, then the angle of incidence is nearl… Answer: 3. μ A For a small-angle prism, with emergent ray normal to the second face, the angle of refraction at the second face is 0. Since... Refraction through a prism 1 answer
In a guitar, two strings A and B made of same material are slightly out of tune and produce beats of frequency 6 Hz. When tension in B is slightly decreased, the beat frequency increases to 7 Hz. If the frequency of A is 530 Hz, the original frequenc… Answer: 2. 524 Hz Frequency of a string f∝√(T) . Decreasing tension of B lowers its frequency. Beat frequency was 6 Hz and rose to 7 Hz afte... Beats 1 answer
The phase difference between displacement and acceleration of a particle in a simple harmonic motion is : Answer: 1. π rad For SHM, x=Asinω t , and acceleration a=-ω²x . The negative sign means acceleration is always opposite in direction to disp... SHM and its equation, phase 1 answer
Two particles of mass 5 kg and 10 kg respectively are attached to the two ends of a rigid rod of length 1 m with negligible mass.The centre of mass of the system from the 5 kg particle is nearly at a distance of : Answer: 3. 67 cm Take the 5 kg mass as the origin. Centre of mass: x_cm=5(0)+10(100)/5+10=1000/15≈67\ cm It lies closer to the heavier mass,... Centre of mass of two-particle system and rigid body 1 answer
Find the torque about the origin when a force of 3j N acts on a particle whose position vector is 2k m. Answer: 3. -6i N m Torque vecτ=vec r×vec F . vecτ=2hat k×3hat j=6(hat k×hat j)=6(-hat i)=-6hat i\ N m Since hat j×hat k=hat i , reversing th... Moment of force, torque 1 answer
Two cylinders A and B of equal capacity are connected to each other via a stop cock. A contains an ideal gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stop cock is suddenly opened.… Answer: 2. adiabatic The system is thermally insulated, so no heat enters or leaves: Q=0 . That makes the process adiabatic. (This is a free... Isothermal and adiabatic processes 1 answer
Which of the following is a basic amino acid ? Answer: 4. Lysine A basic amino acid has an extra basic group (amino) in its side chain. Lysine, H₂N(CH₂)₄CH(NH₂)COOH , has two amino groups... Amino acids, peptide bond, protein structure, denaturation 1 answer
Which of the following is a natural polymer ? Answer: 1. cis-1,4-polyisoprene Natural rubber is cis-1,4-polyisoprene, a polymer made by plants. Poly(butadiene-styrene) (SBR), polybutadie... Amino acids, peptide bond, protein structure, denaturation 1 answer
Sucrose on hydrolysis gives : Answer: 3. α -D-Glucose + β -D-Fructose Sucrose is made of α -D-glucose and β -D-fructose joined through C1 of glucose and C2 of fructose (a... Oligosaccharides: sucrose, lactose, maltose 1 answer
An increase in the concentration of the reactants of a reaction leads to change in : Answer: 4. collision frequency Raising reactant concentration puts more molecules in the same volume, so collisions per second (collision fr... Rate of reaction and factors affecting it 1 answer
The correct option for free expansion of an ideal gas under adiabatic condition is : Answer: 1. q = 0, Δ T = 0 and w = 0 Free expansion means expansion into vacuum, so external pressure is zero and work w=-P_extΔ V=0 . Adiaba... First law: work, heat, internal energy, enthalpy 1 answer
For the reaction, 2Cl(g) → Cl_2(g), the correct option is : Answer: 4. Δ_rH < 0 and Δ_rS < 0 2Cl(g)→ Cl₂(g) forms a Cl-Cl bond. Bond formation releases energy, so Δ_rH<0 . Two particles become one, so... Second law, entropy and spontaneity 1 answer

← Previous

Page 43 of 86