Important Chemistry – 50 Solved Questions
Atomic Structure
Q1. Which transition in hydrogen atom has maximum energy? Ans: n=1 → ∞ (ionization) has
maximum energy.
Atomic Structure
Q2. Write de Broglie wavelength for electron moving with velocity v. Ans: λ = h/mv.
Periodic Properties
Q3. Which element has highest electronegativity? Ans: Fluorine.
Periodic Properties
Q4. Which has smaller size: Na+ or Na? Ans: Na+ (loss of electron → smaller radius).
Periodic Properties
Q5. Arrange F, Cl, Br, I in order of electron affinity. Ans: Cl > F > Br > I.
Bonding
Q6. Bond order of N2 molecule? Ans: 3.
Bonding
Q7. Which has greater dipole moment: NH3 or NF3? Ans: NH3 (due to bond angle and lone pair
direction).
Bonding
Q8. Hybridization of carbon in ethyne? Ans: sp.
Bonding
Q9. Shape of ClF3? Ans: T-shape (VSEPR theory).
Bonding
Q10. Which is more stable: O2+ or O2–? Ans: O2+ (bond order 2.5 > 1.5).
States of Matter
Q11. At constant T, PV = ? Ans: Constant (Boyle’s law).
, States of Matter
Q12. Van der Waals constant ‘a’ is measure of? Ans: Intermolecular attraction.
Thermodynamics
Q13. ∆H < 0 and ∆S > 0. Reaction is? Ans: Always spontaneous.
Thermodynamics
Q14. State Hess’s law. Ans: Enthalpy change is independent of path.
Thermodynamics
Q15. Work done in free expansion of an ideal gas? Ans: Zero.
Equilibrium
Q16. Expression of Ka for HA ■ H+ + A–? Ans: Ka = [H+][A–]/[HA].
Equilibrium
Q17. pH of 0.01 M HCl? Ans: pH = 2.
Equilibrium
Q18. For weak acid, relation between Ka and pKa? Ans: pKa = –log Ka.
Equilibrium
Q19. Common ion effect suppresses? Ans: Ionization of weak electrolyte.
Equilibrium
Q20. Kp vs Kc relation? Ans: Kp = Kc(RT)^∆n.
Electrochemistry
Q21. Nernst equation for single electrode potential? Ans: E = E° – 0.0591/n log(Q).
Electrochemistry
Q22. Which electrode is standard reference? Ans: Standard Hydrogen Electrode (SHE).
Electrochemistry
Q23. Cell with zero free energy change? Ans: At equilibrium, ∆G = 0.
Redox
Q24. Oxidation number of Mn in KMnO4? Ans: +7.
Atomic Structure
Q1. Which transition in hydrogen atom has maximum energy? Ans: n=1 → ∞ (ionization) has
maximum energy.
Atomic Structure
Q2. Write de Broglie wavelength for electron moving with velocity v. Ans: λ = h/mv.
Periodic Properties
Q3. Which element has highest electronegativity? Ans: Fluorine.
Periodic Properties
Q4. Which has smaller size: Na+ or Na? Ans: Na+ (loss of electron → smaller radius).
Periodic Properties
Q5. Arrange F, Cl, Br, I in order of electron affinity. Ans: Cl > F > Br > I.
Bonding
Q6. Bond order of N2 molecule? Ans: 3.
Bonding
Q7. Which has greater dipole moment: NH3 or NF3? Ans: NH3 (due to bond angle and lone pair
direction).
Bonding
Q8. Hybridization of carbon in ethyne? Ans: sp.
Bonding
Q9. Shape of ClF3? Ans: T-shape (VSEPR theory).
Bonding
Q10. Which is more stable: O2+ or O2–? Ans: O2+ (bond order 2.5 > 1.5).
States of Matter
Q11. At constant T, PV = ? Ans: Constant (Boyle’s law).
, States of Matter
Q12. Van der Waals constant ‘a’ is measure of? Ans: Intermolecular attraction.
Thermodynamics
Q13. ∆H < 0 and ∆S > 0. Reaction is? Ans: Always spontaneous.
Thermodynamics
Q14. State Hess’s law. Ans: Enthalpy change is independent of path.
Thermodynamics
Q15. Work done in free expansion of an ideal gas? Ans: Zero.
Equilibrium
Q16. Expression of Ka for HA ■ H+ + A–? Ans: Ka = [H+][A–]/[HA].
Equilibrium
Q17. pH of 0.01 M HCl? Ans: pH = 2.
Equilibrium
Q18. For weak acid, relation between Ka and pKa? Ans: pKa = –log Ka.
Equilibrium
Q19. Common ion effect suppresses? Ans: Ionization of weak electrolyte.
Equilibrium
Q20. Kp vs Kc relation? Ans: Kp = Kc(RT)^∆n.
Electrochemistry
Q21. Nernst equation for single electrode potential? Ans: E = E° – 0.0591/n log(Q).
Electrochemistry
Q22. Which electrode is standard reference? Ans: Standard Hydrogen Electrode (SHE).
Electrochemistry
Q23. Cell with zero free energy change? Ans: At equilibrium, ∆G = 0.
Redox
Q24. Oxidation number of Mn in KMnO4? Ans: +7.
