Name
D-II, Vasant Kunj, New Delhi - 110070
Holiday Home Assignments
Session 2013-14
Class :
: ___________
XI A
Subject : CHEMISTRY
General Instructions:
1. Revise Unit-1 ,2 and 3.
2. Solve problems listed below (Unit-wise)
3. Prepare a project report on an Investigatory project listed below.
SUGGESTED TOPICS
1.
2.
3.
4.
FOR PROJECT WORK
Testing the Hardness of different samples of water
The acidity of different fruits and vegetables.
Detection of Extra elements in different Organic compound.
Techniques of Purification of water.
UNIT-WISE PROBLEMS
UNIT-1 (Some Basic Concepts in Chemistry)
1. Arrange the following in order of increasing masses :
(a) one atom of silver
(b) one mole of calcium
2.
2.
(d) 1022 atoms of carbon
Which of the following contains the maximum number of moles
(a) 224 cm3 of hydrogen at STP
(b) 3.6 g of water
(c) one mole of O2
(c) 112 cm3 of chlorine at STP
(d) 12 g of carbon
500 mL of a 0.250 M Na2SO4 solution was added to an aq. solution of 15 g BaCl2 resulting in the
formation of BaSO4 precipitate. Calculate the amount of BaSO4 formed. Which one of these is the
3.
4.
5.
limiting reagent. (mol mass BaCl2 =208 g mol–1 ; BaSO4 =233 g mol–1)
What weight of pyrolusite , MnO2 , must react with HCl to obtain enough chlorine to fill a container
of 10 L volume at 273 K and 1 atm pressure ?
MnO2 + 4HCl
→
MnCl2 + 2 H2O + Cl2
(molecular mass of MnO2 =87 g mol–1)
The density of a liquid metal is 6.1 g cm–3 . What is the volume occupied by 100 atoms of the
metal if the mass of one atom is = 1.16 × 10–22 g ) .
A compound containing Na, S H and O gave the following results on analysis : Na=14.28% ,
S=9.92% , H= 6.20%.Deduce the molecular formula of the compound if all the H atoms
in the salt are in combination with O as water of crystallization.
UNIT-2 (Periodic Classification and Properties)
1.
The largest atom among , Na , F , Be , Br , Ca is
.........
2.
Arrange Ca , Br , Li , C , O and N in decreasing order of atomic size .
3.
How does ionization energy vary in a group and in a period ? What are isoelectronic ions ?
4.
Among the species I , I+ and I– which one is the largest and why ?
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5.
6.
Arrange the following in increasing order of electron attatchment enthalpies : F , Cl , Br, I
Indicate the group and period to which the elements with atomic numbers 9 , 29 and 31
belong .
7.
Explain the following giving reasons:
(a) The size of a cation is smaller tha n that of its parent atom.
(b) The electron affinity of noble gases is zero.
(c) Boron has a lower first ionization energy than that of beryllium.
(d) The electron affinity of fluorine is less than that of chlorine even though the
Electron affinity decreases down a group.
(e)
Noble gases have very high ionization energies.
UNIT-3 (Structure of Atom)
1.
(a) The maximum number of 3d electron that can have spin quantum number
+1/2 is ____ .
(b) Among X-rays ,visible rays ,infra-red rays and micro waves ,which one has the
highest frequency.
(c) What is the significance of Pauli's Exclusion principle ?
2.
Arrange the orbitals 2s , 3p, 4s, 2p, 3d , 4p in the order of increasing energy .
3.
Write the electronic configuration of Mn (atomic number of Mn=25).
4.
The ground state energy of hydrogen electron is –1312 kJ/mol.What will be the energy
of the electron when it is excited to the second energy level ? Calculate the
wave-length of radiation required to excite the hydrogen electron from the first to
the second energy level.
Given : h = 6.6×10 –34 Js ; Avogadro's number = 6.02×10 23 and
5.
6.
velocity of light = 3×10 8 m/s.
An orbital is represented by the quantum numbers : n = 2 , l = 1 , m = 0 ; what are
the quantum number values of another orbital with the same energy.
What is the designation of this orbital. How many electrons this orbital can
accomodate?
(a) Which of the following are isoelectronic species: K + , Na + , Ca 2+ , F – , Mg 2+ , O 2–
(b) Write the configuration of the following ions : H – ,
Na + , F –
(c) What is the lowest n value that allows g orbitals to exist ?
UNIT-4 (Chemical Bonding and Molecular Structure)
1.
Write the Lewis dot structure for CO 2 .
2.
3.
4.
5.
6.
7.
Predict the shape of BeCl 2 on the basis of VSEPR theory.
Draw the shape of sp 2 hybrid orbitals.
Ethyl alcohol and dimethyl ether are isomeric but have different boiling points. Why ?
The type of bond holding I 2 molecules together in the crystals of I 2 are ....................
BeF 2 is linear but SO 2 is not.Explain
In which of the following chlorides are the bonds covalent : NaCl , BaCl 2 , BCl 3 .
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8.
9.
10.
11.
12.
13.
14.
15.
A molecule has three bond pairs and one lone pair aroud it.The shape of the molecule is
______________ (tetrahedral / pyramidal / planer or octahedral )
Which of the following molecules has a polar bond but zero dipole moment :
SO 2 , CO 2 , H 2 O , NH 3
Molten NaCl is a good conductor of electricity whereas solid NaCl is a non -conductor.
Explain.
What is hybridization ? Explain the shape of BF 3 with the help of a diagram and show
the type of hybrid orbitals
involved.
Arrange the following bonds in order of increasing ionic character
C–H , F–H , Br–H
, Na–I , K–F , Li–Cl
What are sigma and pi bonds. How many sigma and pi bond s are present in ortho-nitro
phenol.
Acetylene is a linear molecule while ethylene is a planar mo lecule.Explain the
difference in the shapes of these molecules on the basis of hybridization .
Predict the dipole moment of
(a)
a molecule of AX 4 type with a square planar geometry.
(b)
16.
17.
18.
a molecule of AX 3 type with a planar triangular geometry.
Explain the concept of resonance.What are the guide lines for writing resonance
structures ?
BeF 2 molecule has a zero dipole moment although Be –F bonds are polar.Explain ?
Explain the following giving reasons:
(a) A sigma bond is stronger than a pi bond.
(b) The bond angle in water is 104.5 o instead of the regular tetradehral angle of 109 o 28'.
(c)
Water has a higher boiling point than H 2 S.
(d) Ionic solids have very high melting points.
(e) Boiling point of noble gases are very low.
Problem Solving Assessment
1.The pH of an aqueous solution of H3PO2 is 1.0.Assuming 100% dissociation the molarity of the
acid
is
(a) 0.1
(b) 0.3
(c) 0.5
(d) data is incomplete
2. In a basic solution which of the following is true
(a) pH = pOH
(b) pH > pOH
(c) pH < pOH
(d) pH = –pOH
3. The volume of hydrogen gas obtained as measured at STP , when 32 g methanol reacts with sodium
metal is
(a) 11.2 L
(b) 22.4 L
(c) 5.6 L
(d) 33.6 L
4. Highest occupied molecular orbital in O2 molecule is
(a)
(c)
* 2p
x
* 2p
x
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(d)
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5.
H for the reaction
CH4 (g) + ½ O2(g)
————>
If Hfo for CH4 is x and that for CH3OH is y , then
CH3OH (l) is negative.
(a) x > y
(b) x=y
(c) x<y
(d) x+y= 0
6. The correct set of quantum numbers of the unpaired electron in chlorine atom is
(Atomic number=17)
(a)
n=2 , l =1 , m=0 , s = +½ or –½
(b)
n=3 , l =1 , m=0 , s = +½ or –½
(c)
n=3 , l =2 , m=0 , s = +½ or –½
(d)
n=2 , l =1 , m=0 , s = +½ or –½
7. Which of the following conditions regarding the chemical process ensures its spontaneity at
all temperatures ?
(a)
H>0, S<0
(b)
H>0, S<0
(c)
H<0, S<0
(d) H < 0 , S > 0
8. Which of the following is not true:
(a) pH + pOH =14
(b) A solution of BeCl2 is acidic in nature
(c) HS– is the conjugate base of H2S
9.
(d) 5 moles of an ideal gas undergoes isothermal expansion at 300 K; the enthalpy
change is 10 kJ.
The number of molecules contained in 16 mg of oxygen is :
(a) 6.02 × 1023
(b) 3.01 × 1023
(c) 3.01 × 1020
(d) 6.02 × 1020
10. The ratio of the energy of the first three orbits of hydrogen atom is :
(a) 1 : 2 : 3
(b) 1 : 4 : 3
(c) 1 : 4 : 6
(d) 1 : 4 : 9
11.
Choose the incorrect statement:
(a) An alkyl halide reacts with alcoholic KOH to form an alkene. The order of the elimination
reactions is 3° halide > 2° halide > 1° halide.
(b) Formation of nitrobenzene from benzene using the nitrating mixture is electrophilic
substitution reaction.
(c) Alkenes are less reactive than alkynes towards addition reactions.
(d) Decarboxylation reactions are used to prepare alkanes.
12.
13.
According to the Huckel rule, an aromatic compound has
(a) (4n + 2)
(b) (4n + 2p)
(c) (2n + 4)
(d) (3n + 3p)
Choose the incorrect statement:
(a) Dipole moment is a vector quantity.
(b) Dipole moment of ammonia is more than that of NF3
(c) Ammonia and water have the same type of hybridization and shape.
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(d) The bond order of N2+ molecule ion is the same as that of O2+
14.
Hydrogen atoms in acetylene are acidic because
(a) acetylene contains the least no. of hydrogen atoms.
(b) acetylene belongs to the class of alkyne with molecular formula CnH2n-2
(c) acetylene has only one hydrogen on each carbon.
(d) sigma electron density of C-H bond in acetylene is nearer to carbon which has
50% ‘s’ character.
15. Equal masses of CH4 and H2 are mixed in an empty chamber at 300 K. The partial pressure of
hydrogen in this chamber as fraction of the total pressure is
(a) 1 / 2
(b) 8 / 9
(c) 1 / 9
(d)
8 / 19
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