HSC Science (General) 12th Standard Board Exam - Maharashtra State Board Question Bank Solutions

An element with density 10 g cm⁻³ forms a cubic unit cell with edge length of 3 × 10⁻⁸ cm. What is the nature of the cubic unit cell if the atomic mass of the element is 81 g mol⁻¹?

The rate constant of a first order reaction increases from 4 × 10⁻² to 8 × 10⁻² when the temperature changes from 27°C to 37°C. Calculate the energy of activation (Ea). (log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)

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?

An element crystallizes in a f.c.c. lattice with a cell edge of 250 pm. Calculate the density if 300 g of this element contains 2 × 10²⁴ atoms. 

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)

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)

What type of battery is mercury cell? Why is it more advantageous than dry cell?

An element with density 2.8 g cm^–3 forms a f.c.c. unit cell with edge length 4 x 10^–8 cm. Calculate the molar mass of the element.

(Given : N_A = 6.022 x 10²³ mol ^–1)

Name the type of cell which was used in Apollo space programme for providing electrical power.

A solution of glucose (molar mass = 180 g mol^–1) in water is labelled as 10% (by mass). What would be the molality and molarity of the solution ? (Density of solution = 1.2 g mL^–1)

Define terms: Fuel cell

Define the following terms: Secondary batteries

Which of the following pairs is an intensive property?

(A) Density, viscosity

(B) Surface tension, mass

(C) Viscosity, internal energy

(D) Heat capacity, volume

In the Arrhenius equation for a first order reaction, the values of ‘A’ of ‘E_a’ are 4 × 10¹³ sec⁻¹ and 98.6 kJ mol⁻¹ respectively. At what temperature will its half life period be 10 minutes?

[R = 8.314 J K⁻¹ mol⁻¹]

A solution of a substance having mass 1.8 x 10^-3 kg has the osmotic pressure of 0.52 atm at 280 K. Calculate the molar mass of the substance used.
[Volume = 1 dm³, R = 8.314 J K^-1 mol^-1]

The boiling point of benzene is 353.23 K. When 1.80 gram of non-volatile solute  was dissolved in 90 gram of benzene, the boiling point is raised to 354.11 K. Calculate the molar mass of solute.
[Kb for benzene = 2.53 K kg mol^-1]

Which of the following is a basic oxide?

(A) SiO₂

(B) P₄O₁₀

(C) MgO

(D) Al₂O₃

55 L atm of work is obtained when 1.0 mole of an ideal gas is compressed isothermally from
a volume of 28.5 L to 18.5 L, the constant external pressure is

(A) 5.05 atm

(B) 5.5 atm

(C) 0.05 atm

(D) 0.55 atm

A metal crystallises into two cubic faces namely face centered (FCC) and body centered (BCC), whose unit cell edge lengths are 3.5 Å and 3.0 Å respectively. Find the ratio of the densities of FCC and BCC.

An organic substance (M = 169 gram mol^–1) is dissolved in 2000 cm³ of water. Its osmotic pressure at 12°C was found to be 0.54 atm. If R = 0.0821 L atm K^–1 mol^–1, calculate the mass of the solute.