HSC Science (General) 12th Standard Board Exam - Maharashtra State Board Important Questions

One mole of an ideal gas is expanded isothermally and reversibly from 10 L to 15 L at 300 K. Calculate the work done in the process.

Calculate the standard enthalpy of formation of CH₃OH_(l) from the following data:

1. \[\ce{CH3OH_{(l)} + 3/2 O2_{(g)} -> CO2_{(g)} + 2H2O_{(l)}ΔH^° = - 726 kJ mol^{-1}}\]
2. \[\ce{C_{(s)} + O2_{(g)} → CO2_{(g)}Δ_cH^° = – 393 kJ mol^{-1}}\]
3. \[\ce{H2_{(g)} + 1/2 O2_{(g)} -> H2O_{(l)}Δ_fH^° = - 286 kJ mol^{-1}}\]

Calculate the standard enthalpy of:

\[\ce{N2H_{4(g)} + H_{2(g)} -> 2NH_{3(g)}}\]

If ΔH⁰(N – H) = 389 kJ mol^–1, ΔH⁰(H – H) = 435 kJ mol^–1, ΔH⁰(N – N) = 159 kJ mol^–1.

Write the correct condition for spontaneity in terms of Gibbs energy.

Calculate the work done during the expansion of 2 moles of an ideal gas from 10 dm³ to 20 dm³ at 298 K in a vacuum.

2000 mmol of an ideal gas expanded isothermally and reversibly from 20 L to 30 L at 300 K, calculate the work done in the process (R = 8.314 JK^–1 mol^–1).

For a certain reaction ΔH⁰ is −224 kJ and ΔS⁰ is −153 J K⁻¹. At what temperature the change over from spontaneous to non-spontaneous will occur?

Write the sign convention of work done during expansion of gas.

Calculate the time required to deposit 2.4 g of \[\ce{Cu}\], when 2.03 A of current passed through \[\ce{CuSO4}\], solution. (At. mass of \[\ce{Cu}\] = 63.5 g mol⁻¹)

Define Intensive property.

Define Adiabatic process.

Calculate the standard enthalpy of combustion of methane if the standard enthalpy of formation of methane, carbon dioxide and water are −74.8, −393.5 and −285.8 kJmol⁻¹ respectively.

How much electricity in terms of Faraday is required to produce 40.0 g of Al from molten Al₂O₃?

(Given: Molar mass of Aluminium is 27 g mol⁻¹.)

Explain a graphical method to determine activation energy of a reaction.

In a first order reaction x → y, 40% of the given sample of compound remains unreacted in 45 minutes. Calculate rate constant of the reaction.

A → B is a first order reaction with rate 6.6 × 10^-5m-s^-1. When [A] is 0.6m, rate constant of the reaction is

• 1.1 × 10^-5s^-1
• 1.1 × 10^-4s^-1
• 9 × 10^-5s^-1
• 9 × 10^-4s^-1

The integrated rate equation for first order reaction is A → products

The rate constant for a first order reaction is 100 s^–1. The time required for completion of 50% of reaction is _______.

(A) 0.0693 milliseconds

(B) 0.693 milliseconds

(C) 6.93 milliseconds

(D) 69.3 milliseconds

The Arrhenius equation is_________________ .

(a)`k=Ae^(RT/E_a)`                                                    

(b)`A=ke^(-E_a/(RT))`

(c)`k=Ae^(-(RT)/E_a)`

(d)`k=Ae^(-E_a/(RT))`

Sucrose decomposes in acid solution to give glucose and fructose according to the first order rate law. The half life of the reaction is 3 hours. Calculate fraction of sucrose which will remain after 8 hours.