Chemistry — Physical Chemistry for the NEET Exam — Spanish candidates

Common failure modes

These are the patterns that cause most candidates to lose marks on this topic. Recognising them in advance is half the work.

• !Forgetting to convert temperature to Kelvin in all thermodynamic and kinetic equations
• !Misapplying the Nernst equation — forgetting that E = E° − (RT/nF) ln Q, with n = moles of electrons transferred
• !Confusing ΔG and ΔG° — ΔG = ΔG° only at standard conditions; otherwise ΔG = ΔG° + RT ln Q
• !Colligative property errors: misapplying the van't Hoff factor i for electrolytes vs non-electrolytes
• !First-order vs second-order half-life confusion in chemical kinetics

Study tips

• 1Build a Physical Chemistry formula sheet: ΔG = ΔH − TΔS; Kp vs Kc relation; Nernst equation; Arrhenius equation; van't Hoff factor; Raoult's law; first/second-order integrated rate laws.
• 2Drill numericals on elevation of boiling point (ΔTb = Kb × m × i) and depression of freezing point (ΔTf = Kf × m × i). NEET frequently tests these with given Kb/Kf values.
• 3Memorise standard electrode potentials of common half-reactions (Zn²⁺/Zn, Cu²⁺/Cu, Fe³⁺/Fe²⁺) — NEET tests cell EMF calculation from these.
• 4For chemical equilibrium, practise ICE table problems (Initial, Change, Equilibrium) for Kc and Kp calculation.
• 5Solve at least 3 past-year NEET Physical Chemistry questions per day in the final month — the pattern repeats.
• 6Los candidatos españoles que se preparan para el NEET pueden aprovechar la similitud léxica entre español e inglés — concéntrate en los falsos amigos y los matices gramaticales que más penalizan.

Sample NEET Chemistry — Physical Chemistry questions

These sample items mirror the format and difficulty of real NEET questions. Practice with thousands more on the free Koydo question bank.

1. 1

   For a first-order reaction, the half-life is:

   • ADependent on the initial concentration
   • B0.693 / kCorrect
   • C1 / k[A]₀
   • Dk / 0.693
   Why this answer?

   For a first-order reaction, the integrated rate law gives t½ = 0.693/k (where k is the rate constant). This is independent of initial concentration — a characteristic of first-order kinetics. For second-order, t½ = 1/(k[A]₀), which depends on initial concentration.

2. 2

   Spontaneity of a reaction at constant T and P is governed by:

   • AΔH < 0 alone
   • BΔS > 0 alone
   • CΔG < 0Correct
   • DΔH > ΔS
   Why this answer?

   A process is spontaneous at constant temperature and pressure if ΔG < 0, where ΔG = ΔH − TΔS. Neither ΔH < 0 nor ΔS > 0 alone is sufficient. Both ΔH and ΔS contribute to ΔG, and temperature determines which term dominates.

3. 3

   The van't Hoff factor (i) for MgCl₂ (assuming complete dissociation) is:

   • A1
   • B2
   • C3Correct
   • D4
   Why this answer?

   MgCl₂ → Mg²⁺ + 2Cl⁻, producing 3 ions per formula unit. The van't Hoff factor i = 3 for complete dissociation. It is used in colligative property calculations: ΔTb = i × Kb × m.

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