Model Question Paper 2024-25

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Questions and Answers

The empirical formula of benzene is

C6H12O6

C6H6 (correct)

C12H22O11

The angular momentum of an electron in the nth orbit is given by:

n²h / (2π)

nxh

nh / π

nh / (2π) (correct)

The maximum number of electrons that can be accommodated in a subshell is given by:

2l + 1

2n²

4l + 2

2(2l + 1) (correct)

The equilibrium constant (K) for the reaction aA+bB⇌cC+dD is given by:

[C]c[D]d / [A]a[B]b Signup and view all the answers

Which of the following is a redox reaction?

CuO+H2→Cu+H2O Signup and view all the answers

The functional group in an alcohol is:

-OH Signup and view all the answers

The number of sigma and pi bonds in benzene are.........respectively.

6, 6 Signup and view all the answers

Which of the following is an alkyne?

Propyne Signup and view all the answers

Which of the following reactions involves the addition of hydrogen to an unsaturated hydrocarbon?

Hydrogenation Signup and view all the answers

Assertion (A): Electrons in the same subshell have the same energy. Reason (R): Electrons in the same subshell are located in orbitals with the same shape.

True Signup and view all the answers

Assertion (A): At equilibrium, the concentrations of reactants and products remain constant over time. Reason (R): At equilibrium, the forward and reverse reactions stop occurring.

True Signup and view all the answers

Explain the significance of the azimuthal and magnetic quantum numbers.

The azimuthal quantum number (l) defines the shape of the orbital and the magnetic quantum number (ml) specifies the orientation of the orbital in space. Signup and view all the answers

Define Ionization enthalpy. Explain the trend of ionization energy across a period and down a group.

Ionization enthalpy is the minimum energy required to remove one electron from an isolated gaseous atom in its ground state. Across a period, ionization energy increases due to increasing effective nuclear charge and decreasing atomic size. Down a group, ionization energy decreases due to increasing atomic size and shielding effect from inner electrons. Signup and view all the answers

State and explain the first law of thermodynamics.

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed. It can be expressed as ΔU = Q - W, where ΔU is the change in internal energy, Q is the heat absorbed by the system, and W is the work done by the system. Signup and view all the answers

Calculate the work done when 2 moles of an ideal gas expand reversibly and isothermally at a temperature of 300 K from an initial volume of 10 L to a final volume of 30 L. Assume the gas behaves ideally.

The work done during reversible isothermal expansion is given by W = -nRTln(V2/V1) = -(2 mol)(8.314 J/mol*K)(300 K)ln(30 L/10 L) = -11.5 kJ. Signup and view all the answers

Explain Carius method to estimate the percentage of halogen in an organic compound.

The Carius method involves heating a known mass of the organic compound with fuming nitric acid in a sealed tube. The halogen present in the compound is converted to its corresponding silver halide, which is then filtered, dried, and weighed. The percentage of halogen is calculated based on the mass of the silver halide formed. Signup and view all the answers

What is isomerism? Write the functional isomers of propanone.

Isomerism refers to the phenomenon where two or more compounds have the same molecular formula but different structural arrangements of atoms. The functional isomers of propanone (CH3COCH3) are propanal (CH3CH2CHO) and methyl acetate (CH3COOCH3). Signup and view all the answers

Alkynes are more acidic than alkanes why? Explain the Markovnikov's rule with an example.

Alkynes are more acidic than alkanes because the carbon-carbon triple bond creates a more acidic hydrogen. The sp hybridization of the alkyne carbon creates a more electronegative carbon, pulling electron density away from the hydrogen and making it more acidic. Markovnikov's rule states that in the addition of a protic acid (HX) to an unsymmetrical alkene, the hydrogen atom of HX adds to the carbon with more hydrogen atoms, while the halide group adds to the carbon with fewer hydrogen atoms. For example, the addition of HBr to propene results in the formation of 2-bromopropane, where the bromine atom adds to the carbon with fewer hydrogen atoms. Signup and view all the answers

State Pauli exclusion principle and Hund's rule of maximum multiplicity. Or a) State Heisenberg's Uncertainty Principle. b) Calculate wave number of radiations having frequency of 4× 10¹¹ Hz.

The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers. Hund's rule of maximum multiplicity states that electrons will individually occupy each degenerate orbital within a subshell before pairing up in any one orbital. Heisenberg's uncertainty principle states that it is impossible to determine both the position and momentum of a particle with absolute certainty. The wave number of radiations having a frequency of 4x10^11 Hz is calculated as 1/λ = 1/(c/ν) = 4x10^11 Hz/3x10^8 m/s = 1.33 x 10^3 m⁻¹. Signup and view all the answers

A) Define electron gain enthalpy. Explain why electron gain enthalpy of fluorine is less negative than that of chlorine. b) Give the cause of periodicity in periodic properties.

Electron gain enthalpy is the change in energy when an electron is added to a neutral gaseous atom to form a negative ion. The electron gain enthalpy of fluorine is less negative than that of chlorine because fluorine is a smaller atom with a higher effective nuclear charge which leads to stronger attraction of the added electron. Periodic properties like ionization enthalpy, electron gain enthalpy, and electronegativity show periodic trends due to the repeating patterns of electron configurations across periods and groups. Signup and view all the answers

A) Explain Gibbs free energy and its significance in predicting the spontaneity of a reaction. b) What will be the sign of ΔS for the reaction 2Cl(g) → Cl2(g) ?

Gibbs free energy (G) is a thermodynamic potential that combines enthalpy (H) and entropy (S) to predict the spontaneity of a process at constant temperature and pressure. ΔG = ΔH - TΔS, where ΔG is the change in Gibbs free energy, ΔH is the change in enthalpy, T is the temperature, and ΔS is the change in entropy. If ΔG is negative, the process is spontaneous (favorable), if ΔG is positive, the process is non-spontaneous (unfavorable), and if ΔG is zero, the process is at equilibrium. For the reaction 2Cl(g) → Cl2(g), the entropy change (ΔS) will be negative because the number of gas molecules decreases, leading to a less disordered state. Signup and view all the answers

A) Balance the following equation in acidic medium. Cr2O72+C2O42→Cr3++CO2 b) Calculate Oxidation number of Cr in K2Cr2O7.

The balanced equation in acidic medium is: Cr2O72- + 3C2O42- + 14H+ → 2Cr3+ + 6CO2 + 7H2O The oxidation number of Cr in K2Cr2O7 is +6. Signup and view all the answers

A) Write the IUPAC name of CH3-CH=CH-CH2OH. b) Arrange the following in increasing order of acidic strength and give reason for your answer C13CCOOH, Cl2CHCOOH and ClCH2COOH

The IUPAC name of CH3-CH=CH-CH2OH is But-2-en-1-ol. The increasing order of acidic strength: ClCH2COOH < Cl2CHCOOH < Cl3CCOOH. This order is based on the electron-withdrawing nature of the chlorine atoms. More chlorine atoms increase the electron-withdrawing effect, making the carboxyl group more acidic. Signup and view all the answers

Study Notes