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

Calculate the standard enthalpy of the reaction, \[\ce{SiO2_{(s)} + 3C_{(graphite)} -> SiC_{(s)} + 2CO_{(g)}}\] from the following reactions:

1. \[\ce{Si_{(s)} + O2_{(g)} -> SiO2_{(s)}}\], Δ_rH⁰ = −911 kJ
2. \[\ce{2C_{(graphite)} + O2_{(g)} -> 2CO_{(g)}}\], Δ_rH⁰ = −221 kJ
3. \[\ce{Si_{(s)} + C_{(graphite)} -> SiC_{(s)}}\], Δ_rH⁰ = −65.3 kJ

What happens if external potential applied becomes greater than E°cell of electrochemical cell?

The rate constant of a first order reaction increases from 2 × 10⁻² to 4 × 10⁻² when the temperature changes from 300 K to 310 K. Calculate the energy of activation (E_a).

(log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)

Write applications of electrochemical series.

Give SI unit of resistivity.

Write an equation that shows the relationship between molar conductivity and degree of dissociation of weak electrolyte.

Write applications of Kohlrausch’s Law.

What is the mass of copper metal produced at cathode during the passage of 2.03 A current through the CuSO₄ solution for 1 hour. Molar mass of Cu = 63.5 g mol^–1.

Calculate molar conductivities at zero concentration for CaCl₂ and NaCl.

Given: molar ionic conductivities of Ca²⁺, Cl^–, Na⁺ ions are respectively, 104, 76.4, 50.1 Ω–1 cm^–2 mol^–1

Write two applications of fuel cells.

Draw a neat labelled diagram of a lead accumulator.

Define electrochemical series. 

What is calcination?

Purification of aluminium by electrolytic refining is carried out by

(a)Hoope process

(b)Hall process

(c)Baeyer process

(d)Serperck process

Draw a neat, well labelled diagram of electrolytic cell for extraction of aluminium

Identify molecularity of following reaction:

\[\ce{C2H5I_{(g)} -> C2H_{4(g)} + HI_{(g)}}\]

What is half life of first order reaction if time required to decrease concentration of reactants from 0.8 M to 0.2 M is 12 hours?

For the reaction 2NOBr → 2NO₂ + Br₂, the rate law is rate = k[NOBr]₂. If the rate of a reaction is 6.5 × 10^–6 mol L^–1 s^–1, when the concentration of NOBr is 2 × 10^–3 mol L^–1. What would be the rate constant of the reaction?

A reaction occurs in the following steps:

Step 1: \[\ce{NO_{2(g)} + F_2 -> NO2F_{(g)} + F_{(g)}}\] (slow)

Step 2: \[\ce{F_{(g)} + NO_{2(g)} -> NO_2F}\] (Fast)

1. Write the equation of overall reaction.
2. Write the rate law.
3. Identify reaction intermediate.

Define molecularity of reaction.