Class - XI
Subject : Chemistry
Time : 3 hrs. Marks.
75
Section A : Descriptive question
1. a) Write down the basic postulates of
kinetic theory of gases. 5
b) Deduce PV=nRT equation for ideal gases. 5
c) At 270c specific mass of gas
along with a solid substance has the total volume 100L. When its temperature is
increased to 540C, its presssure is doubled and its volume is 59.3
L. Find the volume of the solid substance. 5
Or,
a) State the modern periodic law. Discuss
the position of Hydrogen in the periodic table. 2+3
b) Write down the Dalton's law of partiaal pressure Deduce the
relation between partial pressure of a gas and mole fraction. 2+3
c) Define Normality ? From 250 cm3
of 0.5 M NaOH solution what vvolume of deci-molar Na2CO3
solution would be made ? 2+3
2. a) Write down
the fundamental postulates of Bohr's atom model. 5
b) Explain ionic character of covalent
bond and covalent character of ionic bond. 4
c) What is ionic bond ? The percentage of
C & H in a compound is 54.54% and 9.09%. respectively.The
rest of the compound is O. If its vapour density is 44, then determine the
molecular formula. 1+5
Or,
a) Explain Ostwald's dilution law. Deduce Henderson's equation for
calculating the PH of a basic
buffer so1n. 4
b) What is La-Chatelier's principle ?
Explain the effect of Temperature and pressure on chemical equilibrium
according to this principle. 2+3+3
c) To prepare a buffer soln of 4.75 PH,
how many moles of sodium propionate is to be added with 0.02 mol propanoic acid
in a 1.0 dm3 ? 3
3. a) What are
sigma and pi bonds ? Write down some differences between them. 2+3+3
b) What is electronegativity ? Why does
the electronegativity increases as the atomic number increases from left to right
of the elements of the same period of a periodic table. 2+3
c) Calculate the oxxidation number of Fe and Cu in [Fe (CN)6]3-
and [Cu(NH3)4]2+ respectively.
d) A 15 cm3 solution of 0.3 M
KMnO4 mixed with dil H2SO4 can oxidize 25 cm3
of H2O2 Soln. Find the molar concentration of
H2O2 in soln. 3
Or,
a) What is nuclear fission and nuclear
fusion ? Write down the differences between them. 2+3
b) Write down the electronic configuration
of the following ions. 3
Cu2+ (29)
Fe2+ (26)
Mn2+ (25)
c) Write short notes on : 4
i) Pauli's
exclusion principle.
ii) RMS
velocity.
d) + ? +
+ ?+
H s
Section
B : Short type question.
4. a) What is
metallic bond ? Explain with example. 3
b) Why is HCl polar ? 2
Or,
a) Describe SP3 hybridization
with example. 3
b) NCl5 does not exist but PCl5
exists -Why ? 2
5. a) CO2
is gaseous but SiO2 solid -Why ? 3
b) Which one is more ionic and why? KCl or
CaCl2 . 2
Or,
a) Write the causes for the inertness of
inert gases. 3
b) Write two differences between Empirical
formula and Molecular formula. 2
6. a) What are
possible and what are not ? 3d, 2d, 6s 3
b) What is isotope and isobar ? 2
Or,
a) Describe "Diagonal
relationship." 3
b) Find out the strength of 10% Na2CO3
in terms of molarity. 2
7. a) What is mole
fraction ? 2
b) Balance this reaction : 3
K2Cr2O7
+ KI+ H2SO4 Cr2
(SO4)3 + K2SO4 + H2O + 12.
Or,
a) What is polarisation ? 2
b) H2O liquid but H2S
is gas ? 3
8. a) What is heat
of neutralisation ? 2
b) What types of bond are present in the
following compounds. 3
i) CH4 ii) Ca Cl2 iii) (H2O)n
Or,
a) Find the position of Sc (21) and K (19)
in the periodic table. 2
b) Write down three differences between
oxidation number and valency ? 3
9. a) Al f3
is ionic compound, Al Cl3 has covalent character-explain. 3
b) What is hydrogen bond ? 2
Or,
a) At 200c and 740 mm pressure
0.842 gm of a gas has the volume 400 ml. What is its molecular mass ? 3
b) What is oxidising agent ? 2
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