107 public questions tagged with this topic.
The US and U.S.S.R. were engaged in direct correct for Cold War bipolarity superpowers as per NCERT Cold War Era chapter.
Ref: NCERT Political Science Class XII Chapter 1 Cold War Era explains Cold War bipolarity Cuban Missile Crisis superpowers consequences clearly.
Surplus in BoP refers to a correct per microeconomics basics; central problems scarcity choice opportunity cost.
Ref: NCERT Economics Class XI Chapter 1 Introduction to Microeconomics explains central problems scarcity choice PPC opportunity cost concepts clearly.
Government budget is an annual statement correct per microeconomics basics; central problems scarcity choice opportunity cost.
Ref: NCERT Economics Class XI Chapter 1 Introduction to Microeconomics explains central problems scarcity choice PPC opportunity cost concepts clearly.
Central bank prints currency in India. correct per microeconomics basics; central problems scarcity choice opportunity cost.
Ref: NCERT Economics Class XI Chapter 1 Introduction to Microeconomics explains central problems scarcity choice PPC opportunity cost concepts clearly.
India is the biggest producer of correct per microeconomics basics; central problems scarcity choice opportunity cost.
Ref: NCERT Economics Class XI Chapter 1 Introduction to Microeconomics explains central problems scarcity choice PPC opportunity cost concepts clearly.
'Which of the following' means 'There is a cattle into' in context; usage confirms synonymy.
Ref: Cambridge Dictionary vocabulary context confirms word meaning compiled gathered collected from authentic manuscript sources accurately verified standard reference.
**Bohr's quantization** angular momentum L = m v r = n h/2π, for n=2 L=2h/2π= h/π=2.11×10⁻³⁴ J·s, for n=5 L=5h/2π, de Broglie λ = h/p, p= m v, for first orbit v=2.2×10⁶ m/s, λ= h/(m v)=6.6×10⁻³⁴/(9.1×10⁻³¹×2.2×10⁶)=3.3×10⁻¹⁰ m, circumference 2πr=3.33×10⁻¹⁰ m, one wavelength fits for n=1. Thomson’s model does not include a nucleus; it proposes a uniform positive charge distribution, unlike Rutherford’s nuclear model. Using E_n = -13.6/n² eV, r_n = n² a₀, L = n h/2π, R = R₀ A^¹/³, BE = Δm c² and 1 u = 931.5 MeV, evaluation yields Described as a plum pudding model, consistent with Bohr model and
Ref: NCERT > Physics Book > Atoms and Nuclei > De Broglie Hypothesis and Quantization in Bohr Model
**Internal energy change** ΔU = Q - W, for same initial and final states ΔU same regardless of path, but Q and W differ, e.g., isothermal expansion from V₁ to V₂ ΔU=0 Q=W=n R T ln(V₂/V₁), adiabatic expansion between same volumes ΔU=-W, Q=0, different Q,W same ΔU if same T change, illustrating state vs path functions. Reversible processes are quasi-static and lack dissipation, not involving rapid changes or friction. Option A is incorrect as rapid changes lead to irreversibility. Using first law ΔU = Q - W, W = ∫ P dV, isobaric W = P ΔV, isothermal W = n R T ln(V₂/V₁), adiabatic
Ref: NCERT > Physics Book > Thermodynamics > Heat Transfer Work Distinction and Internal Energy Change
**Reversibility** reversible process can be reversed by infinitesimal change, no entropy production, quasi-static without friction, e.g., Carnot cycle reversible, irreversible processes involve friction, free expansion, heat transfer across finite temperature difference, entropy increases, most real processes irreversible. In an adiabatic process ( Δ Q = 0 ), temperature changes (e.g., decreases during expansion), not remains constant (isothermal). Option B is incorrect. Using first law ΔU = Q - W, W = ∫ P dV, isobaric W = P ΔV, isothermal W = n R T ln(V₂/V₁), adiabatic P V^γ = const and η = 1
Ref: NCERT > Physics Book > Thermodynamics > Cyclic Processes and Reversibility Concepts
**Specific heat capacity** c = Q/(m ΔT) (J/kg·K), molar C = Q/(n ΔT), heat required to raise temperature, Q = m c ΔT, for water c=4186 J/kg·K, latent heat L = Q/m for phase change at constant temperature, fusion L_f and vaporization L_v, Q = m L, e.g., ice melting L_f=3.34×10⁵ J/kg, water vaporization 2.26×10⁶ J/kg. In an adiabatic process ( Δ Q = 0 ), temperature can change (e.g., decreases during expansion), as internal energy adjusts via work ( Δ U = -Δ W ). Option B is incorrect as temperature is not constant. Using first law ΔU = Q - W, W =
Ref: NCERT > Physics Book > Thermodynamics > Specific Heat Capacity and Latent Heat
**Carnot engine** reversible engine operating between T_h and T_c has maximum efficiency η =1 - T_c/T_h, T in kelvin, e.g., T_h=400 K T_c=300 K η=0.25, real engines less due to irreversibilities, second law defines direction of spontaneous processes and entropy increase. Reversible processes require quasi-static conditions and no dissipation, not common in nature where irreversibility dominates. Option C is incorrect. Using first law ΔU = Q - W, W = ∫ P dV, isobaric W = P ΔV, isothermal W = n R T ln(V₂/V₁), adiabatic P V^γ = const and η = 1 - T_c/T_h, evaluation yields They are common in natur
Ref: NCERT > Physics Book > Thermodynamics > Second Law Heat Engines and Kelvin-Planck
Dynamic lift (e.g., on airplane wings) results from a pressure difference due to faster airflow above (Bernoulli’s principle), not viscosity or gravitational force alone. The incorrect statement is that it’s due to viscosity.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.
