1. Rock salt is often sprinkled on frozen roads and
walkways to melt ice. This practice is effective
primarily because the salt:
(a) Decreases the freezing point of the water.
(b) Breaks the covalent bonds within the water
molecules.
(c) Increases the temperature of the water.
(d) Eliminates the hydrogen bonds between the
water molecules.

 
2. A lubricant is a substance introduced to reduce
friction between moving surfaces.A good lubricant
possesses the following characteristics :-
1. High boiling point.
2. Low freezing point.
3. High resistance to oxidation.
4. High tribo-electric effect.
Select the correct answer using the code given
below
(a) 1 and 3 only (b) 1, 2 and 3 only
(c) 2 and 4 only (d) 1, 2, 3 and 4

 
3. Which of the following statements describes the
difference between endothermic and exothermic
chemical reactions :-
(a) Energy is absorbed in endothermic reactions but
is released in exothermic reactions.
(b) Energy is conserved in endothermic reactions but
is not conserved in exothermic reactions.
(c) Endothermic reactions involve changes in the
nucleus of an atom, but exothermic reactions do not
involve changes in the nucleus.
(d) Endothermic reactions occur when electrons are
shared between atoms, but exothermic reactions
occur when electrons are transferred between
atoms.

 
4. Potassium Permanganate is a poisonous salt that
forms dark purple crystals and is purple-red when
dissolved in water. Potassium Permanganate is used
for purifying drinking water, because
(a) it is a sterilising agent means it eliminates or kills
all forms of microbial life including transmissible
agents such as fungi, bacteria, viruses, spore forms
etc.
(b) it dissolves the impurities of water which are
biological and chemical.
(c) it is a reducing agent means it is the substance
that causes the reduction of another element.
(d) it is an oxidising agent means it has the ability to
add oxygen, remove hydrogen or remove electrons
from an element or compound.

 
5. The international emphasis on the recycling of
aluminum has been successful primarily because :-
(a) Strict laws associated with recycling enacted in
many states enforce the return of aluminum cans.
(b) There is an ethical incentive for the consumers to
recycle aluminum cans.
(c) The extraction of aluminum from ore uses a
significantly greater amount of energy than
recycling.
(d) Mining aluminum ore has become unprofitable
under current environmental laws.

 
6. Consider the following statement-
1. Magnetite is chemically formulated as Fe2O3.
2. Odisha has the largest desposits of Manganese.
3. Nickel is used to harden steel.
4. Raipur and Bastar is one of the diamond bearing
region in India.
Which of the above statement is/are correct?
(a) 1, 2 and 3 only (b) 1, 2 and 4 only
(c) 3 and 4 only (d) 1, 2, 3 and 4

 
7. Which of the following statements is right
explanation about ‘Oxygen toxicity’ :-
(a) It is a medical condition caused by exposure to
oxygen at high pressure.
(b) It is a medical condition caused by deficiency of
oxygen at high altitude.
(c) It is a medical condition caused by deficiency of

oxygen and exposure of carbon monoxide.
(d) It is a medical condition caused by deficiency of
oxygen and exposure of carbon dioxide.

 
8. Consider the following statement about Lamp
Black:
1. It was traditionally produced by collecting soot
from oil lamps.
2. It is the most pure form of carbon allotrope.
3. The root is used in making printing ink, shoe
polish and eye – root or kajal.
Which one of the above statement is/are correct?
(a) 1 only (b) 1 and 2 only
(c) 2 and 3 only (d) 1, 2 and 3
9. Solids may be considered to be either crystalline
or non-crystalline. The basic difference between
them is that a crystal, in contrast to a non-crystal :-
(a) has a sharp melting point.
(b) has an irregular array of atoms.
(c) exhibits double refraction.
(d) has a completely regular atomic or molecular
structure.

 
10. Which greenhouse gases are included in the
Kyoto protocol?
(a) Carbon Dioxide, Methane, Nitrous Oxide,
Hydrofluorocarbons (HFCs), perfluorocarbons (PFCs),
and Sulphur Hexafluoride.
(b) Carbon Dioxide, Methane, HFCs, PFCs,
Tetrafluoro Methane, Nitrogen Trifluoride
(c) Carbon Dioxide, Methane, Nitrous Oxide, HFCs,
Hexafluoro Ethane, Nitrogen Trifluoride
(d) Carbon Dioxide, Methane, PFCs, Sulphur
Hexafluoride, Tetrafluoro Methane, Nitrogen
Trifluoride

 

Explanation:

 

Q.1 :a
Sprinkling salt on ice makes it melt, which is why
rock salt is used to make walkways and roadways
safer after a snowstorm. The reason it works is
because it raises the melting point of ice. At a
molecular level, the rate of freezing is lowered below
the (constant) rate of melting, because the spacing
between the water molecules is increased.

 
Q.2 :b
High boiling point
Low freezing point.
High resistance to oxidation.
Tribo electric effect is contact electrification.
For example- Rubbing glass with fur.

 
Q.3 :a
Many chemical reactions release energy in the form
of heat, light, or sound. These are exothermic
reactions. Exothermic reactions may occur
spontaneously and result in higher randomness or
entropy (ΔS > 0) of the system. They are denoted by
a negative heat flow (heat is lost to the
surroundings) and decrease in enthalpy (ΔH < 0). In
the lab, exothermic reactions produce heat or may
even be explosive. There are other chemical
reactions that must absorb energy in order to
proceed. These are endothermic reactions.
Endothermic reactions cannot occur spontaneously.
Work must be done in order to get these reactions to
occur. When endothermic reactions absorb energy, a
temperature drop is measured during the reaction.
Endothermic reactions are characterized by positive
heat flow (into the reaction) and an increase in
enthalpy (+ΔH).

 
Q.4 :d
Potassium permanganate has the ability to “oxidize”
soluble manganese and iron in drinking water to an
insoluble manganese dioxide and iron oxide that can
be removed by filtration.

 
Q.5 :c
The widespread use of recycled aluminum saves
energy and reduces pollution, because mining and
processing raw bauxite ore to extract the aluminum
it contains is very energy and waste intensive.
Specifically,
Each one ton of aluminum cans produced
from recycled cans saves five tons of
bauxite;
The reuse of aluminum cans reduces air
pollution by 99% and energy consumption by
95% compared with the production of virgin
aluminum from bauxite; and
The 54 billion cans that the United States
recycled in 2006 saved the equivalent of 15
billion barrels of crude oil.

 
Q.6 :c
– Magnetite chemically formulated as Fe3O4.
– Hematite – Fe2O3

 
Q.7 :a

 
Q.8 :d
Carbon black or lamp black is produced by
such as tar, coal tar, vegetable oil etc.
It is a form of amorphous carbon. Lamp black
was traditionally produced by collecting root
form oil lamps and used as kajal.
The International Agency for Research on
cancer (IARC) finds that carbon black is
possibly carcinogenic to humans.

 
Q.9 :d
A crystal or crystalline solid is a solid material whose
constituent atoms, molecules, or ions are arranged
in an orderly repeating pattern extending in all three
spatial dimensions.
Crystalline solids exhibit cleavage: that is, when you
break them, the nature of the break indicates the
crystal structure. Thus, grinding a crystal of NaCl
(which is cubic) inevitably produces small cubes of
NaCl.
Noncrystalline solids such as glass break into
randomly-shaped pieces. Noncrystalline solids such
as glass soften as the temperature increases and
have no sharply defined melting point. On the other
hand, quartz, which has the same chemical
composition as glass but is crystalline, melts sharply
at around 1650 degrees Celsius.

 
Q.10 :a
Under the Kyoto Protocol, 37 industrialized
countries and the European Community (the
European Union-15, made up of 15 states at
the time of the Kyoto negotiations) commit
themselves to binding targets for GHG
emissions. The targets apply to the four

greenhouse gases carbon dioxide (CO2),
methane (CH4), nitrous oxide (N2O), sulphur
hexafluoride (SF6), and two groups of gases,
hydrofluorocarbons (HFCs) and
perfluorocarbons (PFCs).[50] The six GHG are
translated into CO2 equivalents in
determining reductions in emissions. These
reduction targets are in addition to the
industrial gases, chlorofluorocarbons, or
CFCs, which are dealt with under the 1987
Montreal Protocol on Substances that
Deplete the Ozone Layer.

 

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