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Chemistry Formulae

CHEMISTRY - FORMULA

By Gyanpoints
NEET/MH-CET Formulae sheet

1. SOME BASIC CONCEPTS OF CHEMISTRY

  • Number of molecules: In \(W(g)\) of substance: \[ N = \frac{W(g)}{GMM} \times N_A \]
  • Molality (m): \[ m = \frac{\text{No. of moles of solute}}{\text{Mass of solvent in kg}} \]
  • Number of molecules at S.T.P: In \(V\) litre of gas: \[ N = \frac{V}{22.4} \times N_A \]
  • Number of gram atoms: \[ = \frac{W(g)}{GAM \text{ (gram atomic mass)}} \]
  • Number of gram molecules: \[ = \frac{W(g)}{\text{Gram molecular mass}} \]
  • Dilution formula: \[ M_1 V_1 = M_2 V_2 \] For mixing two solutions of the same substance: \[ M_1 V_1 + M_2 V_2 = M_3 (V_1 + V_2) \] Molarity can be directly calculated from % by mass (w/w) if density is known: \[ \text{Molarity} = \frac{\% \times 10 \times d}{GMM} \]
  • Mass of 1 atom of element A: \[ = \frac{GAM}{N_A} \]
  • Mass of 1 molecule of substance A: \[ = \frac{MM \text{ (Molar mass)}}{N_A} \]
  • Temperature Relation: \[ T(K) = T(^\circ C) + 273.15 \]
  • Relative atomic mass: \[ = \frac{\text{Mass of an atom of the element}}{\frac{1}{12} \times \text{Mass of an atom of carbon (C-12)}} \]
  • Number of molecules in \(n\) moles of substance: \[ N = n \times N_A \]
  • Mass % of an element in a compound: \[ = \frac{\text{Mass of that element in 1 mole of the compound}}{\text{Molar mass of the compound}} \times 100 \]
  • Mass percent: \[ = \frac{\text{Mass of solute}}{\text{Mass of solution}} \times 100 \]
  • Molality from Mole Fraction: \[ m = \frac{X_B \times 1000}{X_A \times M_A} \] where \(M_A\) is the mass of the solvent.
  • Molarity (M): \[ = \frac{\text{No. of moles of solute}}{\text{Volume of solution in litres}} \]
  • Avogadro's No: \[ N_A = 6.022 \times 10^{23} \]
  • Temperature Relation: \[ T(^\circ F) = \frac{9}{5} T(^\circ C) + 32 \]
  • Molecular mass: \[ = 2 \times \text{vapour density} \]
  • Mole fraction of A: \[ = \frac{\text{No. of moles of A}}{\text{No. of moles of solution}} \]

2. STRUCTURE OF ATOM

  • Wavelength of matter wave: \[ \lambda = \frac{h}{mv} \quad ; \quad \lambda = \frac{h}{p} \quad ; \quad \lambda = \frac{h}{\sqrt{2Em}} \] Where \(E\) = Kinetic energy
  • Nodes:
    Total number of nodes = \(n - 1\)
    Radial nodes = \(n - l - 1\)
    Angular nodes = \(l\)
  • Number of neutrons: \(= A - Z\)
  • Shells and Subshells:
    Number of subshells in \(n^{th}\) shell = \(n\)
    Number of orbitals in \(n^{th}\) shell = \(n^2\)
    Number of electrons in \(n^{th}\) shell = \(2n^2\)
    Number of orbitals in subshell = \(2l + 1\)
    Number of electrons in subshell = \(2(2l + 1)\)
  • Energy of quantum of radiation: (Planck's quantum theory) \[ E = h\nu \]
  • Einstein's photoelectric equation: \[ h\nu = h\nu_0 + \frac{1}{2}m_e v^2 \]
  • Line spectrum of hydrogen: \[ \bar{\nu} = \frac{1}{\lambda} = 109677 \left( \frac{1}{n_1^2} - \frac{1}{n_2^2} \right) \text{cm}^{-1} \]
  • Bohr’s model of hydrogen atom:
    • Frequency of radiation absorbed or emitted: \[ \nu = \frac{\Delta E}{h} = \frac{E_2 - E_1}{h} \]
    • Orbit angular momentum of an electron: \[ mvr = \frac{nh}{2\pi} \]
    • Energy of stationary states: \[ E_n = -2.18 \times 10^{-18} \left(\frac{Z^2}{n^2}\right) \text{ J} \]
    • Radii of the stationary states/orbits: \[ r_n = 52.9 \left(\frac{n^2}{Z}\right) \text{ pm} \]
  • Energy gap between two orbits: \[ \Delta E = R_H \left( \frac{1}{n_i^2} - \frac{1}{n_f^2} \right) \] Where \(R_H = 2.18 \times 10^{-18}\text{ J}\)
  • Atomic number (Z): Number of protons = Number of electrons in a neutral atom
  • Heisenberg’s uncertainty principle: \[ \Delta x \times \Delta p \ge \frac{h}{4\pi} \quad ; \quad \Delta x \times m\Delta v \ge \frac{h}{4\pi} \]
  • Speed of light: \[ c = \nu \lambda \]
  • Mass Number (A): Number of protons + Number of neutrons

3. STATE OF MATTER

  • Van der Waals Equation: \[ \left(P + \frac{an^2}{V^2}\right)(V - nb) = nRT \]
  • Combined Gas Equation: \[ \frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2} \]
  • Dalton’s Law of partial pressures: \[ P_{Total} = P_1 + P_2 + P_3 + .... \]
  • Ideal gas equation: \[ PV = nRT \quad \text{and} \quad d = \frac{PM}{RT} \]
  • Charles’s Law: \[ \frac{V_1}{T_1} = \frac{V_2}{T_2} \quad \text{(at constant P and n)} \]
  • Avogadro’s Law: \[ V = kn \quad \text{(at constant P and T)} \]
  • Partial Pressure: \[ P_i = x_i P_{total} \]
  • Boyle’s Law: \[ P_1 V_1 = P_2 V_2 \quad \text{(at constant T and n)} \]
  • Compressibility factor: \[ Z = \frac{PV}{RT} \quad \text{(for 1 mole of Gas)} \]

4. THERMODYNAMICS

  • First law of thermodynamics: \[ \Delta U = q + W \]
  • Enthalpy of reaction: \[ \Delta H^o = \sum \Delta H^o_f (\text{products}) - \sum \Delta H^o_f (\text{reactants}) \] By convention heat of formation of every element in its standard state is arbitrarily assumed to be zero.
    \[ \Delta H^o_{sub} = \Delta H^o_{fus} + \Delta H^o_{vap} \]
  • Heat Capacity:
    • Specific heat capacity: \(s = \frac{q}{m \Delta T}\)
    • Heat capacity: \(C = \frac{q}{\Delta T}\)
    • Molar heat capacity: \(c_m = \frac{q}{n \Delta T}\)
  • Energy changes:
    • \(q_v \rightarrow\) heat exchange at constant volume: \(\Delta U = q_v\)
    • \(q_p \rightarrow\) heat exchange at constant pressure: \(\Delta H = q_p\)
  • Enthalpy: \[ H = U + pV \]
  • Relation between \(\Delta H\) and \(\Delta U\): \[ \Delta H = \Delta U + p\Delta V \quad \text{Or} \quad \Delta H = \Delta U + \Delta n_g RT \]
  • Other relations: \[ C_p - C_v = R \] \[ \Delta S = \frac{q_{rev}}{T} \] \[ \Delta G = \Delta H - T \Delta S \] \[ \Delta G^o = -RT \ln K \]
Atomicity \(\gamma\) \(C_p\) \(C_v\)
Monoatomic 5/3 5R/2 3R/2
Diatomic 7/5 7R/2 5R/2
Triatomic non linear 4/3 4R 3R

5. EQUILIBRIUM

  • (1) \(K_w = K_a \times K_b\)
  • (2) \(K = \frac{[A^+][B^-]}{[AB]}\)
  • (3) \(K_{sp} = [A^+]^x [B^-]^y\)
  • (4) \(\Delta G^o = -2.303 RT \log K\)
  • (5) \(K_a = \frac{[A^-][H_3O^+]}{[HA]}\) and \(K_b = \frac{[B^+][OH^-]}{[BOH]}\)
  • (6) \(K_w = [H^+][OH^-] = 10^{-14} \text{ at } 25^\circ C\)
  • (7) \(pH = -\log [H^+]\)
  • (8) \(pK_w = pH + pOH = 14 \text{ at } 25^\circ C\)
  • (9) \(K_p = K_c (RT)^{\Delta n}\)
  • (10) Hydrolysis of salts:
    • Salt of strong acid and weak base: \(pH = \frac{1}{2}[pK_w - pK_b - \log c]\)
    • Salt of weak acid and strong base: \(pH = \frac{1}{2}[pK_w + pK_a + \log c]\)
    • Salt of weak acid and weak base: \(pH = \frac{1}{2}[pK_w + pK_a - pK_b]\)
  • (11) Equilibrium constant, \(K = \frac{K_a}{K_b}\)
  • (12) \(K_a \text{ or } K_b = C\alpha^2\)
  • (13) Concentration quotient, \(Q = \frac{[C]^c [D]^d}{[A]^a [B]^b}\)

6. SOLID STATE

  • (1) Density of Cubic Crystal System: \[ \rho = \frac{Z \times M}{a^3 \times N_A} \text{ g.cm}^{-3} \] Where, \(Z\) = number of atoms per unit cell, \(N_A\) = Avogadro's Number, \(M\) = Gram atomic weight of element (\text{g. mol}^{-1}), \(a\) = edge length.
  • Contribution of each atom present on the body centre = 1
  • Contribution of each atom present on the edge centre = 1/4
  • (5) Seven crystal systems with dimensions:
    • Cubic: \(\alpha = \beta = \gamma = 90^\circ, a = b = c\)
    • Tetragonal: \(\alpha = \beta = \gamma = 90^\circ, a = b \neq c\)
    • Orthorhombic: \(\alpha = \beta = \gamma = 90^\circ, a \neq b \neq c\)
    • Monoclinic: \(\alpha = \gamma = 90^\circ, \beta \neq 90^\circ, a \neq b \neq c\)
    • Hexagonal: \(\alpha = \beta = 90^\circ, \gamma = 120^\circ, a = b \neq c\)
    • Rhombohedral or trigonal: \(\alpha = \beta = \gamma \neq 90^\circ, a = b = c\)
    • Triclinic: \(\alpha \neq \beta \neq \gamma \neq 90^\circ, a \neq b \neq c\)

7. SOLUTIONS

  • (1) Depression in freezing point: \[ \Delta T_f = K_f \times m \] \[ K_f = \frac{R T_f^2 M_A}{1000 \Delta H_{fusion}} \]
  • (2) Dissociation of solute: \[ A_n \rightarrow nA \] \[ i = 1 + (n - 1)\alpha \] where \(\alpha\) = degree of dissociation
  • (3) Raoult's law: \[ P_A = P_A^0 X_A \] \[ P_B = P_B^0 X_B \] \[ P_{sol} = P_A + P_B = P_A^0 X_A + P_B^0 X_B \]
  • (4) Osmotic pressure: \[ \pi = CRT \] For isotonic solution, \(\pi_1 = \pi_2\)
  • (5) \[ \frac{1}{P} = \frac{Y_A}{P_A^0} + \frac{Y_B}{P_B^0} \]
  • (6) Relative lowering of vapour pressure: \[ \frac{P_A^0 - P_{sol}}{P_A^0} = \chi_B \]
  • (10) Van't Hoff factor (\(i\)): \[ i = \frac{\text{Experimental colligative property (observed)}}{\text{Calculated (normal) colligative property}} \] \[ \Delta T_b = i \times K_b \times m \] \[ \Delta T_f = i \times K_f \times m \] \[ \pi = iCRT \]
  • (11) Association of Solute: \[ nA \rightarrow A_n \] \[ i = 1 - \alpha + \frac{\alpha}{n} \] where \(\alpha\) = degree of association
  • (12) Henry's Law: \[ p = K_H \cdot X \] where \(p\) = partial pressure, \(K_H\) = Henry's constant, \(X\) = Mole fraction

8. ELECTROCHEMISTRY

  • (1) Ohm's law: \[ V = RI \implies R = \rho \frac{l}{a} \]
  • (2) Conductance: \[ G = \frac{1}{R} \] Specific conductance (conductivity): \(\kappa = \frac{1}{\rho}\)
  • (3) Cell constant: \[ = \frac{l}{a} \]

10. SURFACE CHEMISTRY

  • (1) Freundlich Adsorption isotherm: \[ \frac{x}{m} = kP^{1/n} \quad (n \ge 1) \]
  • (2) Langmuir Adsorption isotherm: \[ \theta = \frac{KP}{1 + KP} \quad \text{Or,} \quad \frac{P}{x/m} = \frac{1}{a} + \frac{b}{a}P \]
  • (3) \[ \frac{x}{m} = KC^{1/n} \]
  • (4) Zeta potential: \[ Z = \frac{4\pi\eta\mu}{D} \]

11. HYDROGEN

  • (1) At. Wt. of H: \[ = \frac{\% H^1 \times 1 + \% H^2 \times 2 + \% H^3 \times 3}{100} \]
  • (2) Vapour density of a gas = Molar mass of gas / Molar mass of \(H_2\)
  • (3) Molecular wt. = \(2 \times \text{V.D.}\)
  • (4) Vol. Strength of \(H_2O_2\): \[ = \text{Molarity} \times 11.2 \] \[ = \text{Normality} \times 5.6 \]

12. S-BLOCK ELEMENTS

  • (1) General Electronic Configuration \(ns^{1-2}\).
  • (2) Atomic Radii increases down the group.
  • (3) Hydration enthalpy decreases down the group.
  • (4) Ionization enthalpy decreases down the group.
  • (5) On reaction with oxygen give oxide, peroxide and superoxides.
  • (6) On reaction with water produces hydroxide and hydrogen.
  • (7) Some important compounds and their general names:
Name Chemical Formula Prepared by
Caustic Soda NaOH Electrolysis in Castner-Kellner cell
Washing Soda Na₂CO₃, 10H₂O Solvay's process
Baking Soda NaHCO₃ Solvay's process
Glauber's Salt Na₂SO₄, 10H₂O NaCl + H₂SO₄
Microcosmic salt Na(NH₄)HPO₄ NH₄Cl + Na₂HPO₄
Potash or Pearl Ash K₂CO₃ Leblanc Process
Caustic potash KOH Electrolysis of KCl
Quick lime CaO Decomposition of CaCO₃
Slaked lime Ca(OH)₂ Hydrolysis of CaO
Gypsum CaSO₄, 2H₂O CaCl₂ + H₂SO₄
Plaster of Paris CaSO₄, ½ H₂O By heating gypsum

15. ORGANIC CHEMISTRY

Relations for the estimation of elements in organic compounds:

  • % of C: \[ = \frac{12}{44} \times \frac{\text{Mass of CO}_2 \text{ formed}}{\text{Mass of the compound}} \times 100 \]
  • % of H: \[ = \frac{2}{18} \times \frac{\text{Mass of H}_2\text{O formed}}{\text{Mass of the compound}} \times 100 \]
  • % of N (Dumas's method): \[ = \frac{28}{22400} \times \frac{\text{Volume of N}_2 \text{ at NTP}}{\text{Mass of compound}} \times 100 \]
  • % of N (Kjeldahl's method): \[ = \frac{1.4 \times \text{Normality of acid used} \times \text{Volume of acid used}}{\text{Mass of the compound}} \]
  • % of X (Halogens): \[ = \frac{\text{At. mass of X}}{(108 + \text{At. mass of X})} \times \frac{\text{Mass of AgX formed}}{\text{Mass of the compound}} \times 100 \]
  • % of S: \[ = \frac{32}{233} \times \frac{\text{Mass of BaSO}_4 \text{ formed}}{\text{Mass of the compound}} \times 100 \]
  • % of P: \[ = \frac{62}{222} \times \frac{\text{Mass of Mg}_2\text{P}_2\text{O}_7 \text{ formed}}{\text{Mass of the compound}} \times 100 \]

Order Effects:

  • Inductive effect (+I effect): \(\text{-CH}_3 < \text{-C}_2\text{H}_5 < \text{-C}_3\text{H}_7 < \text{-CH(CH}_3\text{)}_2 < \text{-C(CH}_3\text{)}_3\)
  • Inductive effect (-I effect): \(\text{-NO}_2 > \text{-CN} > \text{-SO}_3\text{H} > \text{-COOH} > \text{-F} > \text{-Cl} > \text{-Br} > \text{-I} > \text{-OR} > \text{-OH} > \text{-NH}_2 > \text{-C}_6\text{H}_5\)
  • Stability of free radical: \(3^\circ > 2^\circ > 1^\circ\)
  • Heat of hydrogenation of alkenes: 1-butene > cis-2-butene > trans-2-butene
  • Leaving nature in Nucleophilic substitution reaction: \(\text{ArSO}_3^- > \text{ROSO}_3^- > \text{CH}_3\text{COO}^- > \text{CN}^- > \text{OH}^- > \text{MeO}^- > \text{NH}_2^-\)

16. ALCOHOLS, PHENOLS AND ETHERS

Preparation of Alcohols:

  • (i) From alkenes
    • (a) By acid catalysed hydration in accordance with Markownikov's rule.
    • (b) By hydroboration-oxidation: \[ 3\text{CH}_3\text{CH}=\text{CH}_2 + \frac{1}{2}(\text{B}_2\text{H}_6) \xrightarrow{\text{H}_2\text{O}_2/\text{OH}^-} \text{CH}_3\text{CH}_2\text{CH}_2\text{OH} + \text{B(OH)}_3 \]

[DIAGRAM PLACEHOLDER]
Flowchart illustrating Phenol conversion to various products (Anisole bromination, nitration, Friedel-Craft alkylation/acylation).

[DIAGRAM PLACEHOLDER]
Flowchart showing Phenol to benzene via Zn dust, then to toluene, benzaldehyde, and benzoic acid.

[DIAGRAM PLACEHOLDER]
Flowchart showing Phenol to Aniline and Benzene Diazonium Chloride.

Differentiate between organic compounds:

  • (a) Alcohols and phenols: Phenol on reaction with neutral FeCl₃ gives purple colour whereas alcohols do not. \[ 6\text{C}_6\text{H}_5\text{OH} + \text{Fe}^{3+} \rightarrow [\text{Fe(OC}_6\text{H}_5)_6]^{3-} (\text{Purple colour}) + 6\text{H}^+ \]

18. AMINES

Methods of Preparation of Amines:

  • (i) By reduction of nitro compounds (catalytically with Raney Ni, Pt or Pd): \[ \text{R-NO}_2 + 3\text{H}_2 \xrightarrow{\text{Ni, Pt or Pd}} \text{R-NH}_2 + 2\text{H}_2\text{O} \] \[ \text{Ar-NO}_2 + 3\text{H}_2 \xrightarrow{\text{Ni, Pt or Pd}} \text{Ar-NH}_2 + 2\text{H}_2\text{O} \]
  • Reduction with active metals (Sn/HCl or Fe/HCl): \[ \text{R-NO}_2 + 3\text{H}_2 \xrightarrow{\text{Sn/HCl or Fe/HCl}} \text{R-NH}_2 + 2\text{H}_2\text{O} \] \[ \text{Ar-NO}_2 + 3\text{H}_2 \xrightarrow{\text{Sn/HCl or Fe/HCl}} \text{Ar-NH}_2 + 2\text{H}_2\text{O} \]
  • (ii) By Hofmann's method (Ammonolysis of alkyl halides): \[ \text{RX} \xrightarrow{\text{NH}_3} \text{RNH}_2 (1^\circ) \xrightarrow{\text{RX}} \text{R}_2\text{NH} (2^\circ) \xrightarrow{\text{RX}} \text{R}_3\text{N} (3^\circ) \xrightarrow{\text{RX}} \text{R}_4\text{N}^+\text{X}^- \text{(Quaternary salt)} \]

19. HALOALKANES AND HALOARENES

Reactions:

  • Swarts reaction: \[ \text{R-Br} + \text{AgF} \rightarrow \text{R-F} + \text{AgBr} \]
  • Hunsdiecker Reaction: \[ \text{CH}_3\text{COOAg} + \text{Br}_2 \xrightarrow{\text{CCl}_4} \text{CH}_3\text{Br} + \text{AgBr} + \text{CO}_2 \]

[DIAGRAM PLACEHOLDER]
Sandmeyer's reaction, Gattermann reaction, Balz-Schiemann reaction flowcharts from Diazonium Chloride.

[DIAGRAM PLACEHOLDER]
Flowchart of Nucleophilic Substitution Reactions of Ethyl Bromide with various reagents.

Reaction with Metals:

  • (i) Wurtz reaction: \[ \text{RX} + 2\text{Na} + \text{XR} \xrightarrow{\text{Dry ether}} \text{R-R (alkane)} + 2\text{NaX} \]
  • (iii) Reaction with Mg: \[ \text{C}_2\text{H}_5\text{Br} + \text{Mg} \xrightarrow{\text{Dry ether}} \text{C}_2\text{H}_5\text{MgBr (Grignard's reagent)} \]

20. HYDROCARBONS

Preparation of Alkanes:

  • (1) Wurtz reaction: \[ 2\text{CH}_3\text{CH}_2\text{Br} + 2\text{Na} \xrightarrow{\text{Dry ether}} \text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_3 + 2\text{NaBr} \]
  • Frankland reaction: \[ 2\text{RX} + \text{Zn} \rightarrow \text{R-R} + \text{ZnX}_2 \]
  • (2) From Grignard reagent (RMgX): \[ \text{RMgX} + \text{HOH} \rightarrow \text{RH} + \text{Mg(OH)X} \] \[ \text{RMgX} + \text{R'OH} \rightarrow \text{RH} + \text{Mg(OR')X} \] \[ 2\text{RMgX} + \text{R'NH}_2 \rightarrow \text{RH} + \text{Mg(NHR')X} \]
  • (3) Sabatier-Senderens reduction: \[ \text{R-CH}=\text{CH}_2 + \text{H}_2 \xrightarrow{\text{Ni}/\Delta} \text{R-CH}_2\text{-CH}_3 \] \[ \text{R-C}\equiv\text{CH} + 2\text{H}_2 \xrightarrow{\text{Ni}/\Delta} \text{R-CH}_2\text{-CH}_3 \]
  • (4) Decarboxylation: \[ \text{CH}_3\text{COONa} + \text{NaOH} \xrightarrow{\text{CaO}/\Delta} \text{CH}_4 + \text{Na}_2\text{CO}_3 \]

Reactions:

  • Combustion: \[ \text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O} \quad , \quad \Delta H = -217.0 \text{ K cal/mole} \]
  • Halogenation: \[ \text{CH}_4 + \text{Cl}_2 \xrightarrow{\text{UV}} \text{CH}_3\text{Cl} + \text{HCl} \] Reactivity of Halogens: \(\text{F}_2 > \text{Cl}_2 > \text{Br}_2 > \text{I}_2\)
    Rate of replacement of Hydrogens: \(3^\circ > 2^\circ > 1^\circ\)

21. POLYMERS

Addition Polymers:

  • (a) Low density polythene (LDP): \[ n\text{CH}_2=\text{CH}_2 \xrightarrow[350-750K, 1000-2000 \text{ atm}]{\text{traces of O}_2} -(\text{CH}_2-\text{CH}_2)_n- \]
  • (b) High density polythene (HDP): \[ n\text{CH}_2=\text{CH}_2 \xrightarrow[333-343K, 6-7 \text{ atm}]{\text{Ziegler Natta catalyst}} -(\text{CH}_2-\text{CH}_2)_n- \]
  • (c) Polyacrylonitrile (Orlon): \[ n\text{CH}_2=\text{CHCN} \xrightarrow[\text{Peroxide catalyst}]{\text{Polymerisation}} -(\text{CH}_2-\text{CH(CN)})_n- \]
  • (d) Polytetrafluoroethene (Teflon): \[ n\text{CF}_2=\text{CF}_2 \xrightarrow[\text{High pressure}]{\text{catalyst}} -(\text{CF}_2-\text{CF}_2)_n- \]

Condensation Polymers (Polyamides):

  • (a) Nylon 6, 6: Condensation of hexamethylenediamine with adipic acid.
  • (b) Nylon 6: Heating caprolactam with water.
Name of polymer Class of polymer Name/s of monomer/s Uses
Dynel Copolymer Vinyl chloride and acrylonitrile Human hair wigs
Glyptal Copolymer Ethylene glycol and phthalic acid In paints
Thiokol Condensation Ethylene chloride and sodium tetrasulphide Rubber
Superglue Homopolymer Methyl \(\alpha\)-cyanoacrylate Glue
Kevlar Polyamide condensation Terephthalic acid chloride and p-phenylene diamine Bullet proof vests and helmets
Nomex Polyamide condensation m-phthalic acid and m-dinitrobenzene Protective clothes for race car drives
Lexan Polycarbonate Ester condensation Diethylcarbonate and bisphenol A Bullet proof windows and helmets
Polyurethane (Thermocole) Copolymer Toluene diisocyanate and ethylene glycol Padding and building insulation
Saran Copolymer Vinyl chloride and vinylidene chloride Bumpers


Source 2: NEET 38 Years Chemistry PYQs

Covalent Bond, Electrovalent Bond, Lattice Enthalpy and Octet Rule

1. Amongst the following, the total number of species NOT having eight electrons around central atom in its outer most shell, is: \(\text{NH}_3, \text{AlCl}_3, \text{BeCl}_2, \text{CCl}_4, \text{PCl}_5\) [MR] (2023)
a. 1
b. 3
c. 2
d. 4

2. Which of the following species contains equal number of \(s\) and \(\pi\)-bonds? [MR] (2015 Re)
a. \((\text{CN})_2\)
b. \((\text{CH})_2(\text{CN})_2\)
c. \(\text{HCO}_3^-\)
d. \(\text{XeO}_4\)

3. Which one of the following molecules contains no \(\pi\) bond? (2013)
a. \(\text{SO}_2\)
b. \(\text{NO}_2\)
c. \(\text{CO}_2\)
d. \(\text{H}_2\text{O}\)

4. Which of the following is electron-deficient? (2013)
a. \((\text{CH}_3)_2\)
b. \((\text{SiH}_3)_2\)
c. \((\text{BH}_3)_2\)
d. \(\text{PH}_3\)

5. Energy and radius of first Bohr orbit of \(\text{He}^+\) and \(\text{Li}^{2+}\) are
[Given \(R_H = 2.18 \times 10^{-18} \text{ J}, a_0 = 52.9 \text{ pm}\)]
a. \(E_n(\text{Li}^{2+}) = -19.62 \times 10^{-18} \text{ J}\); \(r_n(\text{Li}^{2+}) = 17.6 \text{ pm}\); \(E_n(\text{He}^{+}) = -8.72 \times 10^{-18} \text{ J}\); \(r_n(\text{He}^{+}) = 26.4 \text{ pm}\)
b. \(E_n(\text{Li}^{2+}) = -8.72 \times 10^{-18} \text{ J}\); \(r_n(\text{Li}^{2+}) = 26.4 \text{ pm}\); \(E_n(\text{He}^{+}) = -19.62 \times 10^{-18} \text{ J}\); \(r_n(\text{He}^{+}) = 17.6 \text{ pm}\)
...

8. Which among the following electronic configurations belong to main group elements?
A. \([\text{Ne}]3s^1\)
B. \([\text{Ar}]3d^3 4s^2\)
C. \([\text{Kr}]4d^{10} 5s^2 5p^5\)
D. \([\text{Ar}]3d^{10} 4s^1\)
E. \([\text{Rn}]5f^0 6d^2 7s^2\)
Choose the correct answer:
a. B and E only
b. A and C only
c. D and E only
d. A, C and D only

9. Dalton's Atomic theory could not explain which of the following?
a. Law of conservation of mass
b. Law of constant proportion
c. Law of multiple proportion
d. Law of gaseous volume

Bond Parameters and Dipole Moment

14. Which of the following molecules has “NON ZERO” dipole moment value? (2024 Re)
a. \(\text{CCl}_4\)
b. \(\text{HI}\)
c. \(\text{CO}_2\)
d. \(\text{BF}_3\)

16. Match List-I with List-II: (2024 Re)

List-I (Molecule)List-II (Bond enthalpy kJ/mol)
A. HClI. 435.8
B. N₂II. 498
C. H₂III. 946.0
D. O₂IV. 431.0

Choose the correct answer:
a. A-III, B-IV, C-I, D-II
b. A-IV, B-I, C-III, D-II
c. A-IV, B-III, C-II, D-I
d. A-IV, B-III, C-I, D-II

VSEPR Theory

45. Match List I with List II. (2024)

List-I (Compound)List-II (Shape/geometry)
A. NH₃I. Trigonal Pyramidal
B. BrF₅II. Square Planar
C. XeF₄III. Octahedral
D. SF₆IV. Square Pyramidal

49. Identify the wrongly matched pair. (2020-Covid)
a. \(\text{SF}_6\) - Octahedral
b. \(\text{BeCl}_2\) - Linear
c. \(\text{NH}_3\) - Trigonal pyramidal
d. \(\text{PCl}_5\) - Trigonal planar

Valence Bond Theory, Hybridisation

80. \(\text{BF}_3\) is planar and electron deficient compound. Hybridization and number of electrons around the central atom, respectively are: (2021)
a. \(sp^3\) and 6
b. \(sp^2\) and 6

83. The hybridisation of atomic orbitals of nitrogen in \(\text{NO}_2^+\), \(\text{NO}_3^-\) and \(\text{NH}_4^+\) respectively are: [MR] (2016-II)
a. \(sp\), \(sp^3\) and \(sp^2\)
b. \(sp^2\), \(sp^3\) and \(sp\)
c. \(sp\), \(sp^2\) and \(sp^3\)
d. \(sp^2\), \(sp\) and \(sp^3\)

MOT, Bonding in Some Homonuclear Diatomic Molecules

108. The correct order of energies of molecular orbitals of \(\text{N}_2\) molecule is: [MR] (2023)
a. \(\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s < \pi 2p_x = \pi 2p_y < \pi^* 2p_x = \pi^* 2p_y < \sigma 2p_z < \sigma^* 2p_z\)
b. \(\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s < \pi 2p_x = \pi 2p_y < \sigma 2p_z < \pi^* 2p_x = \pi^* 2p_y < \sigma^* 2p_z\)
c. \(\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s < \sigma 2p_z < ... \)

Hydrogen Bonding

139. Intramolecular hydrogen bonding is present in (2024)
a. o-Nitrophenol
b. HF
c. m-Nitrophenol
d. p-Nitrophenol

143. Which one shows maximum hydrogen bonding? [MR] (1990)
a. \(\text{H}_2\text{O}\)
b. \(\text{H}_2\text{Se}\)
c. \(\text{H}_2\text{S}\)
d. \(\text{HF}\)

Answer Key

1. (b) 2. (d) 3. (d) 4. (c) 5. (a) 6. (d) 7. (b) 8. (c) 9. (d) 14. (b) 15. (c) 16. (d) 17. (b) 18. (d) 19. (b) 20. (b) 21. (c) 22. (d) 23. (c) 24. (b) 25. (c) 26. (b) 27. (a) 28. (c) 29. (a) 30. (d) 31. (a) 32. (c) 33. (c) 34. (c) 35. (c) 36. (b) 37. (b) 38. (b) 39. (a) 40. (a) 41. (c) 42. (b) 43. (c) 44. (b) 45. (c) 46. (c) 47. (a) 48. (d) 49. (d) 50. (d) 51. (a) 52. (a) 53. (a, d) 54. (b) 55. (a) 56. (c) 57. (b) 58. (a) 59. (b) 60. (d) 61. (a) 62. (d) 63. (a) 64. (c) 65. (b) 66. (a) 67. (c) 68. (c) 69. (d) 70. (d) 71. (d) 72. (c) 73. (d) 74. (c) 75. (b) 76. (a) 77. (b) 78. (b) 79. (b) 80. (b) 81. (b) 82. (d) 83. (c) 84. (c) 85. (a) 86. (a) 87. (c) 88. (b) 89. (a) 90. (b) 91. (d) 92. (c) 93. (c) 94. (d) 95. (b) 96. (b) 97. (b) 98. (b) 99. (b) 100. (d) 101. (a) 102. (a) 103. (a) 104. (a) 105. (b) 106. (a) 107. (b) 108. (b) 109. (c) 110. (a) 111. (d) 112. (c) 113. (b) 114. (b) 115. (a) 116. (c) 117. (b) 118. (a) 119. (a) 120. (b) 121. (c) 122. (a) 123. (b) 124. (c) 125. (a) 126. (a) 127. (a) 128. (c) 129. (a) 130. (c) 131. (a) 132. (a) 133. (d) 134. (b) 135. (b) 136. (d) 137. (b) 138. (c) 139. (c) 140. (a) 141. (a) 142. (c) 143. (a)

Explanations

  • 1. (b) \(\text{AlCl}_3, \text{BeCl}_2\) and \(\text{PCl}_5\) do not obey the octet rule. \(\text{AlCl}_3\) and \(\text{BeCl}_2\) are electron-deficient (6 and 4 valence electrons respectively), whereas \(\text{PCl}_5\) has an expanded octet (10 valence electrons).
  • 2. (d) \((\text{CN})_2\): \(\text{N}\equiv\text{C}-\text{C}\equiv\text{N}\). It contains 3 \(\sigma\) and 4 \(\pi\) bonds.
  • 3. (d) According to the structure of water, it contains only \(\sigma\) bonds.
  • 4. (c) Electron-deficient species have electrons less than 8 in their valence shell. \(\text{(BH}_3)_2\) is diborane which is electron-deficient.
  • 8. (b) Main group elements lie in groups 1, 2 and 13 to 18. \([\text{Ne}]3s^1\) is Na (Group 1), \([\text{Kr}]4d^{10}5s^25p^5\) is I (Group 17).
  • 9. (d) Dalton's theory could not explain the law of gaseous volume (explained by Avogadro's hypothesis).
  • 14. (b) The dipole moment of \(\text{HI}\) is 0.38 D due to the electronegativity difference between H and I. Molecules like \(\text{CCl}_4\) and \(\text{CO}_2\) are symmetric and have zero dipole moment.
  • 49. (d) The structure of \(\text{PCl}_5\) is trigonal bipyramidal having \(sp^3d\) hybridization, not trigonal planar.
  • 80. (b) Geometry of \(\text{BF}_3\) molecule is Trigonal Planar with \(sp^2\) hybridization and 6 valence electrons around the central Boron atom.
  • 83. (c) Hybridisation state = Number of \(\sigma\) bonds + number of lone pairs. \(\text{NO}_2^+\) is \(sp\), \(\text{NO}_3^-\) is \(sp^2\), \(\text{NH}_4^+\) is \(sp^3\).
  • 108. (b) The correct order of energy of MO for \(\text{N}_2\) is \(\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s < \pi 2p_x = \pi 2p_y < \sigma 2p_z < \pi^* 2p_x = \pi^* 2p_y < \sigma^* 2p_z\).
  • 143. (a) \(\text{H}_2\text{O}\) shows maximum H-bonding because each \(\text{H}_2\text{O}\) molecule is linked to four \(\text{H}_2\text{O}\) molecules through H-bonds.

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