HSC Science (Computer Science) 12th Standard Board Exam - Maharashtra State Board Question Bank Solutions for Chemistry

Write any ‘two’ uses of terylene.

Write the reactions involved in the preparation of  PVC

(b) Rate constant ‘k’ of a reaction varies with temperature ‘T’ according to the equation:

`logk=logA-E_a/2.303R(1/T)`

Where E_a is the activation energy. When a graph is plotted for `logk Vs. 1/T` a straight line with a slope of −4250 K is obtained. Calculate ‘E_a’ for the reaction.(R = 8.314 JK⁻¹ mol⁻¹)

Write cell reaction in lead storage battery during discharge.

Consider the reaction

`3I_((aq))^-) +S_2O_8^(2-)->I_(3(aq))^-) + 2S_2O_4^(2-)`

At particular time t, `(d[SO_4^(2-)])/dt=2.2xx10^(-2)"M/s"`

What are the values of the following at the same time?

a. `-(d[I^-])/dt`

b. `-(d[S_2O_8^(2-)])/dt`

c. `-(d[I_3^-])/dt`

300 M mol of perfect gas occupies 13 L at 320 K. Calculate the work done in joules when the gas expands-

(a) isothermally against a Constant external pressure of 0.20atm.

(b) isothermal and reversible process.

(c) into vaccum until the volume of gas is increased by 3L (R=8.314J mol^-1 K^-1)

Write the chemical reaction to prepare novolac polymer.

What is the action of bromine in alkaline medium on

i. CH₃CH₂NO₂

ii. 

Explain the following term: Homopolymers

One mole of a gas expands by 3L against a constant pressure of 3 atmosphere. Calculate the work done in -

(a) L.atmosphere

(b) Joules

(c) Calories

Describe anomalous behaviour of fluorine with the other elements of group 17 wilh reference to :

(a) Hydrogen bonding

(b) Oxidation state

(c) Polyhalide ions

Write balanced chemical equations for action of potassium permanganate on: Hydrogen

Identify the weakest base amongst the following :

(a) p- methoxyaniline

(b) o-toluidine

(c) benzene - 1, 4 - diamine

(d) 4 - aminobenzoic acid

Bakelite is the polymer of:

(a) Benzaldchyde and phenol

(b) Acetaldehyde and phenol

(c) Formaldehyde and phenol

(d) Formaldehyde and benzyl alcohol

Define electrochemical cell

Why does the cell potential of mercury cell remain constant throughout its life?

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.