CHEMISTRY (Theory) sample paper2 Class – XI
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December 18, 2015 |
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CHEMISTRY (Theory)
Class – XI
Time allowed: 3 hours Maximum Marks: 70
General Instructions:
a) All the questions
are compulsory.
b) There are 26 questions in total.
c) Questions 1 to 5 are
very short answer type questions and carry one mark
each.
d) Questions 6 to 10 carry
two marks each.
e) Questions 11 to 22 carry
three marks each.
f) Questions 23 is value based question carrying four marks.
g) Questions 24 to 26 carry
five marks each.
h) There is no
overall choice. However, an internal choice has been provided in one question
of two marks, one
question of three marks and all three questions in five marks each. You have to attempt only one
of the choices in such questions.
i) Use of calculators
is not permitted. However, you may use
log tables if necessary.
1. What is the
maximum number of electrons in f subshell with same spin?
2. Two
litres of an ideal gas at a pressure of 10 atm expands isothermally into a
vacuum until its total volume is 10
litres. How much heat is absorbed and how much work is done in the expansion?
3. “BeH2 molecule has zero dipole moment although the Be-H
bonds are polar” Explain.
4. Give water gas
shift reaction.
5. Arrange the
following metals in the order in which they displace each other from the
solution of their salts. Al, Cu,
Fe, Mg and Zn.
6. What is hydride
gap? Why is heavy water used in nuclear reactors?
7. Though carbon
dioxide is inert and harmless gas, it is thought to be a serious pollutant.
Why?
8. Which of these
electrons experience lowest effective nuclear charge?
a) The Br atom
containing 35 electrons in which 6 electrons are in 2p orbital or
b) 6 electrons in 3p
orbital and 5 electrons in 4p orbital.
9. Write
structural formulas of the following compounds :
a) 3,
4, 4, 5–Tetramethylheptane
b) 2,5-Dimethyhexane
Or
Write the
structural formula of:
a) O-Ethylanisole
b) 2,3 - Dibromo -1
- phenylpentane
10.
a) How change in velocity of a moving particle change
the wavelength of the particle?
b) Give the
difference in the angular momentum of an electron present in 3p and 4p
orbitals?
11. A liquid is in
equilibrium with its vapour in a sealed container at a fixed temperature. The
volume of the
container is suddenly increased.
a) How do rates of evaporation and
condensation change initially?
b) What is the initial effect of the
change on vapour pressure?
12.
a) How would you
distinguish between BeSO4 and BaSO4?
b) Which is thermally
most stable alkaline earth metal carbonate among MgCO3, CaCO3,
SrCO3,
BaCO3? Give reasons.
13. Derive
the structure of :
a) 2-Chlorohexane
b) Pent-4-en-2-ol
c) 3-
Nitrocyclohexene
d) Cyclohex-2-en-1-ol
Or
Why NH3 has a higher dipole moment than NF3?
14. Why is the
entropy of a substance taken as zero at 0 K? calculate the standard Gibbs free
energy
change for the
reaction
N2 (g)
+ 3H2 (g)Û2NH3 (g)
at 298 K.
The Value of
equilibrium constant for the above reaction is 6.6 x 105. [ R=8.314 J K-1 mol-1]
15. Define the
following:
a) Critical
temperature
b) Avogadro law
c) Charles Law
16. What happens when
a) Sodium metal is
dropped in water?
b) Sodium metal is
heated in free supply of air?
c) Sodium peroxide
dissolves in water?
17. Justify giving
reactions that among halogens, fluorine is the best oxidant and among
hydrohalic
compounds, hydroiodic
acid is the best reductant?
19. Explain the principle of paper chromatography?
20. Write a brief
note on the following environmental terms:
i) Acid rain
ii) Eutrophication
iii) Green Chemistry
21.
i) List two
differences between Orbit and Orbital
ii) If an electron is
moving with a velocity 600 m/s which is accurate up to 0.005%nthen
calculate the
uncertainty in its position. [ h=6.626 x 10-34 Js
and mass of electron = 9.11 x 10-
31 kg]
22. Explain in brief
for the following:
i) Anions are bigger
in size than their parent atom.
ii) Oxygen has lesser
first ionization enthalpy than nitrogen
iii) Fluorine has
less negative electron gain enthalpy than chlorine
23. John was arrested
by the custom officials as he was smuggling drugs and caught by x-ray
machines. According
to Roentgen when electrons strike a material in the cathode ray tube, it
produces a ray which
can cause fluorescence in the fluorescent material placed outside the
cathode ray tubes.
These rays were called x-rays. These were not deflected by electric and
magnetic field. It
was used as diagnostic tool in the treatment of diseases and bone fractures.
a) What is the
approx. wavelength of x-rays?
b) Why x-rays are
used to screen luggage’s in airports?
c) How would you
prevent smuggling?
24.
a) The species H2O, HCO3,
HSO4- and NH3 can act both as Bronsted acids and bases. For each
case
give the
corresponding conjugate acid and base.
b) Consider the
following endothermic reaction: 4 2 2 CH (g) + H O (g)⇌CO (g) + 3H (g)
i) Write expression for Kp for the
above reaction.
ii) How will the
equilibrium be affected by?
1. Increasing the
pressure 2. Using a catalyst
Or
a) Predict the
acidic, basic or neutral nature of the following salt: NaCN, KBr, NaNO2, NH4NO3.
b) How many grams of
KBr are added to 1 L of 0.05 M solution of silver nitrate just to start the precipitation of
AgBr? Ksp of AgBr = 5.0 x 10-13
25. With the help of
structures, give the IUPAC names of different chain isomers of alkanes
corresponding to the
molecular formula C6H14.
Or
The preparation of
acetaldehyde by passing mixture of ethene and oxygen under pressure into
aqueous solution of
PdCl2 and CuCl2 as a catalyst is called Wacker’s process.
Acetalydehyde is a
useful chemical
which is used for silvering of mirror. It can be prepared by various methods.
It is
used in the
commercial preparation of acetic acid, ethyl acetate etc. Paraldehyde, a trimer
of
aldehyde is used as
hypnotic. a) Give the best method to prepare acetaldehyde. Give two reasons.
b) Give the
chemical equation for Wacker’s process of preparation of acetaldehyde.
c) Give the
disadvantage of preparing it from ethyne.
26. Give the net
ionic equation for the reaction of potassium dichromate (VI) with sodium
sulphite in
an acid solution to
give chromium (III) ion and the sulphate ion.
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