Sample Paper
Chemistry
CBSE Board for Class
- XI
Maximum Marks allowed: 70 Duration: 3 hrs
General Instructions
1. All questions are compulsory.
2. Question nos. 1 to 8 are very short answer questions and
carry 1 mark each.
3. Question nos. 9 to 18 are short answer questions and
carry 2 marks each.
4. Question nos. 19 to 27 are also short answer questions
and carry 3 marks each
5. Question nos. 28 to 30 are long answer questions and
carry 5 marks each
6. Use log tables if necessary, use of calculators is not
allowed.
1. How many nitrogen atoms are present in 14 g nitrogen
gas?
2. What is the empirical formula of sodium chloride crystal
?
3.Define the bond length.
4. Write Lewis dot structure of CCl4 and PH3.
5.For the process to occur under adiabatic conditions,the
correct condition is:
a.ΔT=0
b. p=0 c.q=0 d. w=0
6.For an isolated system ,ΔU =0 , what will be ΔS ?
7. What is the thermodynamic criterion for the state of
equilibrium ?
8. Can a catalyst change the position of equilibrium in a reaction ?
9. What is the mass of a molecule of carbon -14
dioxide?
10. Is the law of constant proportions applicable to the
nonstoichiometric compounds? Give
reason.
11. Describe hybridization in the case of SF6.
12.Calculate the number of KJ necessary to raise the
temperature of 60.0 g of aluminium from 350C to
550C.Molar heat
capacity of Al is 24 J/mol/K.(atomic mass of Al=27 g/mol)
13. At 450 K,Kp =2.0x1010 /bar for the given reaction at equilibrium.
2SO2(g) +O2 (g) ------------ 2 SO3 (g) ,What is Kc at this temperature?
14.Explain dynamic equilibrium with the help of suitable
example.
15.The equilibrium constant for a reaction is 10.What will
be the value of ΔG0 ?
R=8.314 JK-Mol-,T=300K
16. How can you predict the extant of a reaction with the
help of equilibrium constant ?
17.Draw Molecular orbital diagram of C2 molecule.
18.State Le Chatelier’s principle .Explain its application
in case of increase of temperature .
19. Define a. molality
b.
molarity
c.
mole fraction
20. If the density of methanol is 0.793 kg/L ,what is its
volume needed for making 2.5 M solution ?
21. Define lattice
enthalpy and draw Born Haber cycle for NaCl crystal.
22.Explain the formation of H2 molecule on the basis of
valence bond theory .
23.The reaction of cyanamide , NH2CN ,with dioxygen was
carried out in a bomb calorimeter , and ΔU
was found to be
-742.7 KJ/mol at 298 K.Calculate enthalpy change for the reaction at 298
K.
24. Define entropy . How entropy is important for deciding
the spontaneity of a reaction?
25. Derive the relationship between Kp and Kc .
26. How ionization constant of weak acids is
calculated?
27.What are buffer solutions ?How do these solutions work
?
28. Derive ΔG=ΔH –TΔS
.Explain the conditions for spontaneous reaction .
Or
a.Define Heat capacity and derive Cp- Cv =R.
b.Explain Hess’s law of constant heat summation .
29. a. What do you
mean by significant figures ?
b.How many
significant figures are present in 0.0025,208,5005,126,00 ?
c. Explain
scientific notation .Express the following in the scientific notation:
0.0048,234,000,8008,500.0
d. Round up
the following upto three significant figures :
34.216,10.4107,0.04597,2808
Or
a. Explain Daltons contribution for chemistry with stating
the accepted postulate of his theory.
b. What is average atomic mass ?Give an example .
30.a.Explain common ion effect and how common ion decreases
ionization of a weak acids.
b. Describe
Solubility product of ionic solute BaSO4.
c. What is the
relationship between Ka and Kb ?
Or
Explain different
concepts of acids and bases with example.
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