#neet
- Match List I with List II.List I (Molecule): A. ethane B. ethene C. carbon molecule, C_2 D. ethyneList II (Number and types of bond/s between two carbon atoms): I. one σ-bond and two π-bonds II. two π-bonds III. one σ-bond IV. one σ-bond and one π-bo… Answer: 4. A-III, B-IV, C-II, D-I Key idea: count the bond between the two carbons. Ethane H₃C-CH₃ : one σ bond (III). Ethene: one σ + one π... 1
- For the reaction 2A ⇌ B + C, K_c = 4×10^-3. At a given time, the composition of reaction mixture is : [A]=[B]=[C]=2×10^-3 M.Then, which of the following is correct? Answer: 4. Reaction has a tendency to go in backward direction. Key idea: compare the reaction quotient Q_c with K_c . Q_c=[B][C]/[A]²=frac(... 1
- Match List I with List II.List I (Process): A. Isothermal process B. Isochoric process C. Isobaric process D. Adiabatic processList II (Conditions): I. No heat exchange II. Carried out at constant temperature III. Carried out at constant volume IV. C… Answer: 1. A-II, B-III, C-IV, D-I Key idea: the prefix tells the fixed quantity. Isothermal: constant temperature (II). Isochoric: constant... 1
- Match List I with List II.List I (Quantum Number): A. m_l B. m_s C. l D. nList II (Information provided): I. shape of orbital II. size of orbital III. orientation of orbital IV. orientation of spin of electronChoose the correct answer from the option… Answer: 3. A-III, B-IV, C-I, D-II Key idea: each quantum number gives one property of the electron or orbital. m_l : orientation of the orbi... 1
- Arrange the following elements in increasing order of first ionization enthalpy:Li, Be, B, C, NChoose the correct answer from the options given below: Answer: 3. Li < B < Be < C < N Key idea: ionization enthalpy increases across a period, with exceptions at Be (filled 2s) and N (half-filled... 1
- Among Group 16 elements, which one does NOT show -2 oxidation state? Answer: 1. Po Key idea: metallic character increases down the group, so the -2 state becomes unfavourable. O, S, Se and Te form oxides, sulp... 1
- In which of the following equilibria, K_p and K_c are NOT equal? Answer: 2. PCl_(5(g)) ⇌ PCl_(3(g)) + Cl_(2(g)) Key idea: K_p=K_c(RT)^(Δ n_g) . They are equal only when Δ n_g=0 . 2BrCl⇌ Br₂+Cl₂ : Δ n_g=0 .... 1
- The reagents with which glucose does not react to give the corresponding tests/products areA. Tollen's reagent B. Schiff's reagent C. HCN D. NH_2OH E. NaHSO_3Choose the correct options from the given below: Answer: 4. B and E Key idea: glucose exists mostly as the cyclic hemiacetal, so it gives some but not all aldehyde reactions. Tollens' reage... 1
- Identify the correct reagents that would bring about the following transformation.[structure transformation shown in figure: ring-CH_2-CH=CH_2 → ring-CH_2-CH_2-CHO] Answer: 3. (i) BH₃ (ii) H₂O₂/oversetominusOH (iii) PCC Key idea: the -CH=CH₂ group must become -CH₂CH₂CHO , a terminal aldehyde, which needs... 1
- At any instant of time t, the displacement of any particle is given by 2t-1 (SI unit) under the influence of force of 5N. The value of instantaneous power is (in SI unit): Answer: 2. 10 Key idea: Instantaneous power P=vec F·vec v . Velocity v=d/dt(2t-1)=2 m/s (constant). Then P=Fv=5×2=10 W. Option 2. 1
- A thin spherical shell is charged by some source. The potential difference between the two points C and P (in V) shown in the figure is:(Take 1/4πε_0=9×10^9 SI units) Answer: 1. zero Key idea: For a charged shell, the potential is the same at every point inside and on the surface: V=kq/R . C is the centre... 1
- A thin flat circular disc of radius 4.5 cm is placed gently over the surface of water. If surface tension of water is 0.07 Nm^-1, then the excess force required to take it away from the surface is : Answer: 2. 19.8 mN Key idea: The surface-tension force acts along the line of contact between the disc and the water, which is the circumfer... 1
- A logic circuit provides the output Y as per the following truth table :| A | B | Y ||---|---|---|| 0 | 0 | 1 || 0 | 1 | 0 || 1 | 0 | 1 || 1 | 1 | 0 |The expression for the output Y is : Answer: 4. B Key idea: Read the truth table to see what Y depends on. Y is 1 when B=0 and 0 when B=1 , whatever A is (rows 1 and 3, and rows... 1
- Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.Assertion A : The potential (V) at any axial point, at 2 m distance(r) from the centre of the dipole of dipole moment vector P of magnitude, 4×10^-6… Answer: 4. A is true but R is false. Key idea: Potential of a dipole at an axial point: V=±p/4πε₀r² . Assertion: V=frac9×10⁹×4×10⁻⁶2²=9×10³... 1
- The terminal voltage of the battery, whose emf is 10 V and internal resistance 1 Ω, when connected through an external resistance of 4 Ω as shown in the figure is : Answer: 4. 8 V Key idea: Terminal voltage V=ε-Ir . Current I=ε/R+r=10/4+1=2 A. V=10-2×1=8 V (equivalently IR=2×4=8 V). Option 4. 1
- In the above diagram, a strong bar magnet is moving towards solenoid-2 from solenoid-1. The direction of induced current in solenoid-1 and that in solenoid-2, respectively, are through the directions: Answer: 2. AB and DC Key idea: Lenz's law: the induced current opposes the change in flux, so a solenoid end facing a moving magnet behaves... 1
- In an ideal transformer, the turns ratio is N_p/N_s=1/2. The ratio V_s : V_p is equal to (the symbols carry their usual meaning) : Answer: 3. 2 : 1 Key idea: For an ideal transformer V_s/V_p=N_s/N_p . Given N_p/N_s=1/2 , we get N_s/N_p=2 , so V_s:V_p=2:1 . It is a step-u... 1
- A tightly wound 100 turns coil of radius 10 cm carries a current of 7 A. The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as 4π×10^-7 SI units): Answer: 4. 4.4 mT Key idea: Field at the centre of a circular coil of N turns: B=μ₀NI/2R . B=frac4π×10⁻⁷×100×72×0.1=frac8.8×10⁻⁴0.2≈4.4×10⁻³... 1
- Given below are two statements :Statement I : Atoms are electrically neutral as they contain equal number of positive and negative charges.Statement II : Atoms of each element are stable and emit their characteristic spectrum.In the light of the abov… Answer: 4. Statement I is correct but Statement II is incorrect. Key idea: Check each statement on its own. Statement I: An atom has equal n... 1
- The quantities which have the same dimensions as those of solid angle are : Answer: 2. strain and angle Key idea: Solid angle (like plane angle) is a ratio of two lengths/areas, so it is dimensionless. Strain (change... 1
- If c is the velocity of light in free space, the correct statements about photon among the following are :A. The energy of a photon is E=h.B. The velocity of a photon is c.C. The momentum of a photon, p=h/c.D. In a photon-electron collision, both tot… Answer: 3. A, B, C and D only Key idea: Go through the properties of a photon. A: E=hν . True. B: Speed is c . True. C: p=hν/c=frac hλ . Tru... 1
- A bob is whirled in a horizontal plane by means of a string with an initial speed of ω rpm. The tension in the string is T. If speed becomes 2ω while keeping the same radius, the tension in the string becomes : Answer: 3. 4T Key idea: The tension supplies the centripetal force: T=mω²r . With the same m and r , T∝ω² . Doubling the speed (rpm) gives T... 1
- If x=5≤ft(π t+π/3)m represents the motion of a particle executing simple harmonic motion, the amplitude and time period of motion, respectively, are : Answer: 3. 5 m, 2 s Key idea: Compare with the standard SHM form x=Asin(ω t+φ) . Here A=5 m and ω=π rad/s. Time period T=2π/ω=2π/π=2 s. Ampl... 1
- A thermodynamic system is taken through the cycle abcda. The work done by the gas along the path bc is : Answer: 2. zero Key idea: Work done by a gas is W=∫ P dV , so it is zero when the volume does not change. In the figure, path bc is vertical... 1