HISSAN CENTRAL EXAMINATION-2079(2022)
CHEMISTRY (3011 SET A)
Class: XI
Time: 3 hrs
F.M: 75
Group-B
1) A gas is prepared by boiling yellow phosphorus with a concentrated solution of sodium
hydroxide in an inert atmosphere.
a. Name the reaction.
(1)
b. Balance the reaction using oxidation number method or ion electron
(2)
c. Draw the Lewis dot structure of the gas and predict its geometry
(1)
d. Write the molecular formula of another compound with same geometry
(1)
2) Hydrogen bonding exists in molecules of living organisms. It exists in various tissues, bloods
Skins, bones, etc. The stickiness of glue or honey is also due to hydrogen bonding. Without
hydrogen bonding, water would have existed as a gas. In that case, no life would have been
possible on earth.
a.Why do cotton clothes take a long time to dry as compared to cotton clothes?
(1)
b. Why is the boiling point of ethyl alcohol much higher than that of diethyl ether?
(2)
c. Explain why o-hydroxybenzaldehyde is a liquid at room temperature while
p-hydroxybenzaldeyde is a high melting solid.
(2)
OR
The first simple theory that was put forward to predict the geometry or shape of a covalent
Molecule is known as Valence Shell Electron Repulsion theory (or VSEPR Theory)
a. Interpret the non-linear shape of H2S molecule and non-planar shape of PCl3
(2)
b. Although formation of NH3 and NF3 molecules involve sp3 hybridization, their
bond lengths are smaller than the normal tetrahedral angle.Why?
(2)
c. Give an example of a compound with linear shape.
(1)
3) Nowadays sodium metal is manufactured by using Downs’s cell. It involves the electrolysis of
sodium chloride containing calcium chloride and potassium fluoride.
a. Why is CaCl2 or KF added in the electrolysis of sodium metal?
(1)
b. Find the mass of sodium metal deposited at cathode when 0.1 ampere of current is passed
for half an hour and the process has 75% efficiency.
(2)
c. Name the gas that is obtained as byproduct. Also what happens when the gas is passed in
hot and conc alkaline solution.
(1+1)
4) When a balloon is filled with lighter gas like H2 and He (lighter than air) it rises up due to the
density of air and gas.
a. Deduce the ideal gas equation where the symbols have their usual meanings.
(2.5)
b. The reaction between gaseous NH3 and HBr produces a white solid NH4Br.Suppose a small
quantity of gaseous NH3 and gaseous HBr are introduced simultaneously into opposite ends of an
open tube which is one metre long. Calculate the distance of white solid formed from the end
which was used to introduce NH3
(2.5)
OR
The diagram shown below is a part of periodic table. Study the table and answer the following
questions:
a. Name a transitional metal.
b. Name the element which is gaseous at room temperature.
c. Name two elements which vigorously reacts with water.
d. Name an element whose oxide is basic.
e. Name the element which forms a colorless solid chloride XCl2 (X=element)
(1)
(1)
(1)
(1)
(1)
5) A student performed a volumetric analysis to estimate iodine. This reaction is also called
iodometric titration. The reaction is given below:
I2 + Na 2S2O3→ Na 2S4O6 + NaI
a. Name the underlined compound and write its uses.
(2)
b. How many molecules are contained in 0.35 mole of the underlined compound?
(1)
c. What will happen if I2 was substituted by bromine in above reaction?
(2)
6) Mineral resources of country determine the economic position of a country. The country
which is rich in mineral resources is definitely a prosperous country.
a. What is the significance of leaching in the extraction of aluminum?
(2)
b. Which of the ores can be concentrated by magnetic separation?
(1)
c. Differentiate between roasting and calcination.
(2)
7) The most dreadful disease, cancer, developed by tar is due to presence of some higher boiling
polynuclear hydrocarbons called carcinogenic hydrocarbons. Azo dyes, aromatic amines and
carbamates are also carcinogenic (cancer causing)
a.