HSC Science (Electronics) इयत्ता १२ वी - Maharashtra State Board Important Questions

Define buffer solution.

Explain the amphoteric nature of water.

Derive an expression for maximum work in isothermal reversible expansion of two moles of an ideal gas.

From the given cells:

Lead storage cell, Mercury cell, Fuel cell and Dry cell

Answer the following:

(i) Which cell is used in hearing aids?

(ii) Which cell was used in Apollo Space Programme?

(iii) Which cell is used in automobiles and inverters?

(iv) Which cell does not have long life?

Following reactions occur at cathode during the electrolysis of aqueous silver chloride solution :

`Ag^+(aq)+e^(-)rarrAg(s)" ""      ""       "E^@=+0.80V`

`H^+(aq)+e^(-)rarr1/2H_2(g)" "" "" " E^@=0.00V`

On the basis of their standard reduction electrode potential (E°) values, which reaction is feasible at the cathode and why ?

Why conductivity of an electrolyte solution decreases with the decrease in concentration ?

Calculate Δ_rG^° for the reaction 

Mg (s) + Cu²⁺ (aq) → Mg²⁺ (aq) + Cu (s)

Given : E^°_cell = + 2.71 V, 1 F = 96500 C mol^–1

Obtain the relationship between ΔH and ΔU for gas phase reactions.

Define “zero order reaction”.

Derive the relation between half life and rate constant for a first order reaction

Write two factors that affect the rate of reaction.

For a reaction : 

(i) Write the order and molecularity of this reaction.

(ii) Write the unit of k.

The rate constant for the first-order decomposition of H₂O₂ is given by the following equation:

`logk=14.2-(1.0xx10^4)/TK`

Calculate E_a for this reaction and rate constant k if its half-life period be 200 minutes.

(Given: R = 8.314 JK^–1 mol^–1)

For the hydrolysis of methyl acetate in aqueous solution, the following results were obtained :

(i) Show that it follows pseudo first order reaction, as the concentration of water remains constant.

(ii) Calculate the average rate of reaction between the time interval 30 to 60 seconds.

(Given log 2 = 0.3010, log 4 = 0.6021)

A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90% completion of this reaction.

(log 2 = 0.3010)

Define activation energy.

Define Reference electrode

Derive the relation between half life and rate constant for a first order reaction

In the extraction of Al, impure Al₂O₃ is dissolved in conc. NaOH to form sodium aluminate and leaving impurities behind. What is the name of this process?

A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90% completion of this reaction.

(log 2 = 0.3010)