Physical Chemistry

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Q1. In a reversible process, the change in entropy of the universe is:

Solution:

In a reversible process, the change in entropy of the universe is zero, as the system and surroundings are in equilibrium.

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Q2. Which of the following statements about the quantum mechanical model of the atom is true?

Solution:

In the quantum mechanical model, electrons are described by wave functions, which give the probability of finding an electron in a certain region.

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Q3. Which of the following statements about the rate of reaction is true?

Solution:

The rate of reaction generally increases with increasing concentration of reactants.

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Q4. What is the Ksp of AgCl if the solubility of AgCl in water is 1.0 x 10^-5 M?

Solution:

Ksp = [Ag+][Cl-] = (1.0 x 10^-5)(1.0 x 10^-5) = 1.0 x 10^-10.

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Q5. What is the total number of orbitals in the n=4 shell?

Solution:

The total number of orbitals in a shell is given by n^2. For n=4, it is 4^2 = 16.

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Q6. Which of the following elements has the electronic configuration 1s2 2s2 2p6 3s2 3p6 4s2?

Solution:

Calcium (Ca) has an atomic number of 20, and its electronic configuration is 1s2 2s2 2p6 3s2 3p6 4s2.

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Q7. What is the electronic configuration of the chloride ion (Cl-)?

Solution:

Chloride ion has gained one electron, making its configuration 1s2 2s2 2p6 3s2 3p6.

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Q8. In an isothermal process, the temperature of the system remains constant. What is the work done by the gas during expansion?

Solution:

In an isothermal process, the work done by the gas is given by W = nRT ln(Vf/Vi).

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Q9. If the rate of a reaction doubles when the temperature is increased by 10°C, what is the approximate activation energy (Ea) of the reaction?

Solution:

Using the Arrhenius equation, a rule of thumb states that for every 10°C increase in temperature, the rate doubles if Ea is around 40 kJ/mol.

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Q10. What is the primary reason gases can be compressed much more than liquids or solids?

Solution:

Gases can be compressed due to large intermolecular spaces between particles, unlike liquids and solids.