Class 11 Sample Paper Chemistry (Half Yearly)

SAMPLE
PAPER
Half Yearly Examination

Prepared For
NCERT BASED SYLLABUS
Applicable For
CBSE BOARD AND STATE BOARD USING NCERT

WWW.

HALF YEARLY EXAMINATION
SAMPLE QUESTION PAPER

Class - XI Subject – Chemistry
Time – 3 Hours Maximum Marks- 70

GENERALINSTRUCTIONS:-

(i) Question paper comprises of four sections A, B, C and D.
(ii) There are 33 questions in the question paper and all questions are compulsory.
(iii) Section A: Q1 to Q2 are case based questions having four MCQ or Reason-Assertion type
based on given passage, each carrying 1mark.
(iv) Section A: Q3 to Q16 are MCQ questions, carrying 1mark each.
(v) Section B: Q17 to Q25are short answer questions and carry 2 marks each.
(vi) Section C: Q26 to Q30 are short answer questions and carry 3 marks each.
(vii) Section D: Q 31to Q33 are long answer questions carrying 5 marks each.
(viii) There are no overall choices. However internal choices have been provided.

SECTION-A

1. Read the passage given below and answer the questions:

Binary solutions can be nine different types depending upon the nature of the solute and nature of the
solvent whether solid, liquid or gas. They may be further classified as solid, liquid or gaseous solutions
based on the component which acts as solvent. However, the liquid solutions are the most important.
Both solids and gases dissolve in liquids resulting in homogenous mixture i.e., solutions. The
solubility is governed by no. of factors such as nature of solute and solvent, temperature, pressure etc.
The concentration of the solutions can be expressed in different ways such as molarity, molality, mole
fraction etc. Out of these molality and mole fraction are better as they do not change with the change
in temperature.
The following questions are multiple choice questions with single correct answer. [1x4=4]
i) One molal solution contains one mole of solute in
a. 1000 gm of the solvent

b. One litre of the solvent
c. One litre of the solution
d. 22.4 litre of the solution

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ii) The mole fraction of solute in 2 molal aqueous solution is:
a. 1.77
b. 1.87
c. 0.347
d. 0.0347

iii) A concentration of 1ppm means that:
a. each kilogram of a solution contains 1mg. of the solute.
b. each gram of solution contains 1gm of the solute.
c. each kilogram of solution contains 1gram of solute.
d. each kilogram of solution contains 1 ml solute.

iv) Molality of sucrose solution changes if:
a. temperature is increased
b. some water is added.
c. in both a and b cases.
d. in none of the above cases.

2. Read the passage given below and answer the following questions: [1x4 =4]

An electron in atom can be fully described in terms of certain constants known as quantum numbers.
These are the four out of which principal, azimuthal, magnetic quantum numbers have been derived
from Schrodinger wave equation. However, the spin quantum number arises from the spin of the
electron around its own axis which may be clockwise or anticlockwise in nature.

In the following questions, a statement of assertion followed by a statement of reason is given. Choose
the correct answer out of the four choices:
a. Assertion and Reason both are correct statements and reason is correct explanation for
assertion.
b. Assertion and Reason both are correct statements but reason is not the correct explanation
for assertion.
c. Assertion is correct statement but reason is wrong statement.
d. Assertion is wrong statement but reason is correct statement.

i) Assertion: An orbital can not have more than two electrons and their spin must be opposite.
Reason: No Two electrons in an atom can have same set of all the four quantum numbers
ii) Assertion: The quantized energy of an electron is largely determined by the principal quantum
number.
Reason: The principal quantum number is a measure of the most proabable distance of finding

the electron around the nucleus of an atom.
iii) Assertion: Angular momentum of the electron in 4p orbital is greater than that of in the 3p
orbital.
Reason: Energy of 4th orbit is greater than that of the third orbit.

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iv) Assertion: No two orbitals have the same number of radial nodes.
Reason: No. of radial nodes of any orbital depends upon the value of principal and azimuthal
quantum numbers.

Following questions (Q3-Q16) are multiple choice questions carrying 1 mark each with single correct
answer:

3. Which is the best example of law of conservation of mass?
a. When 6 gm of carbon is heated in vacuum, there is no change in mass
b. 6 gm of Carbon combines with 16 gm of oxygen to form 22 gm of CO2
c. 6 gm of water is completely converted in steam
d. A sample of air is heated at constant pressure when its volume increases but there is no change in
mass.
4. CH4 is burnt in the availability of oxygen. If 5 moles of each of the component is present then which
one is the limiting reactant?
a. CH4
b. O2
c. Both a and b
d. Neither a nor b
5. A sample of Ammonium phosphate (NH4)3PO4 contains 6 moles of hydrogen atoms. The no. of mole
of oxygen atoms in the sample is:
a. 1
b. 2
c. 4
d. 6
6. The ratio of masses of oxygen in the various oxides of nitrogen prove the law of:
a. Reciprocal proportion
b. Multiple proportion
c. Constant proportion
d. Conservation of mass
7. According to the Bohr theory, which of the following transition in the hydrogen atom will give rise to
the least energetic photon?
a. n=6 to n=1
b. n=5 to n=4
c. n=6 to n=5
d. n=5 to n=3
8. In Cu (Atomic no. 29):
a. 13 electrons have spin in one direction and 16 electrons in other direction

b. 14 electrons have spin in one direction and 15 electrons in other direction
c. One electron has spin only in clockwise direction
d. None of the above is correct

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9. Ψ2= 0 represents:
a. A node
b. An orbital
c. Angular wave function
d. Wave function
10. Which one is a set of isoelectronic species?
a. N2, CO2, ‫ି ܰܥ‬
b. N, H2S, CO
c. N2, CO, ‫ି ܰܥ‬
d. Ca, Mg, Cl
11. The IUPAC symbol for the element with atomic number 119 would be
a. Une
b. Unh
c. Uun
d. Uue
12. The first ionization enthalpy of the following elements are in the order
a. C<N<Si<P
b. P<Si<N<C
c. P<Si<C<N
d. Si<P<C<N
13.An element with atomic number 21 is
a. Transition element
b. Alkali metal
c. Halogen
d. Representative element.
14. Which of the following element has the maximum negative electron gain enthalpy?
a. Oxygen
b. Chlorine
c. Fluorine
d. Nitrogen.
15. The screening effect of d electron is
a. Much less than s- electrons
b. Much more than s- electrons
c. Equal to s -electrons.
d. Equal to p- electrons.
16. The most non metallic element among the following is :
a. Be
b. B

c. Mg
d. Al

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Section – ‘B’
The following questions Q 17- Q25 are short answer type questions and carry2 marks each. [2x9 =18]
17. State Avogadro’s law. How does this law help in calculating atomicity of oxygen ?
18. state the law of multiple proportion with suitable example.
19. Write two differences between molality and molarity.
20. Explain why the uncertainty principle is significant only for the motion of subatomic particles and is
negligible for macroscopic object.
OR
What is the wavelength of the light emitted when the electron in a hydrogen atom undergoes
transition from the energy level with n=4 to the energy level n =2.(R = 109678 cm-1)
21. What are the main differences between electromagnetic wave theory and Planck’s quantum theory?
22. Write electronic configuration of Cr (24). Why are the half - filled orbitals more stable?

23. What is screening effect? How does it influence ionization enthalpy?

24. How will you justify the presence of 18 elements in 5 th period and 32 elements in 6th period of modern
periodic table?

25.Write differences between electron gain enthalpy and electronegativity

Section C
The following questions Q.26 to Q.30 are short answer type questions carrying 3marks.

[3x 5 =15]
26. What are the postulates of Daltons atomic theory? How do the law of chemical combinations follow from
it?

27. Conc HCl used in laboratory is 38 % by mass in aqueous solution. What should be the molarity of such
sample of the acid, if the density of the solution is 1.19 gm cm -3. What volume of conc HCl is required to
make 1.0 litre of 0.10 M HCl?

OR

Conc sulphuric acid is 98% H2SO4 by mass and has a density 1.84 gm cm-3, what volume of conc acid is
required to make 5.0 litre of 0. 50M sulphuric acid solution?
28.Derive deBroglie’s equation. How do de Broglie’s wave differ from electromagnetic wave ?

29. Table tennis ball has a mass 10gm and a speed of 90 m /s .If speed can be measured within the accuracy of
4% ,what will be the uncertainty in speed and position ?

30.Give reason for the following.
(i) Noble gases have positive electron gain enthalpy.

(ii)Radius of anion is more than that of the atom.
(iii)Halogens act as good oxidizing agent.

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Section D
Direction :Q. 31 to Q. 33 are long answer type questions, carrying 5 marks each.

31. (a) Write the basic difference between the empirical formula and molecular formula. Explain with suitable
example.
(b) Butyric acid contains only carbon, hydrogen and oxygen. A 4.24 mg of sample of Butyric acid is
completely burnt, it gives 8.45 mg of CO2 and 3.46 mg of H2O. What is the percentage mass of each
component in butyric acid ? If the molecular mass of Butyric acid is 88 u. What is the molecular
formula ?
[2 + 3]
OR

(a) What do you understand by the term Formula Mass ? How does it differ from Molecular Mass?
(b) From 200 mg of CO2, if 10 21 molecules are removed. How many moles of the gas are left ?

32. (a) Show that the circumference of Bohr’s orbit for the H-atom is an integral multiple of the de- Broglies
wavelength of electron revolving around the orbit.

(b) A bulb emits light of wavelength 4500 A0. The bulb is rated as 150 watt & 8 % energy is emitted as
light. How many photons are emitted by the bulb per second ? [ 1 watt = J sec -1 ; h = 6.626 X 10 -34 J
Sec. ]

OR
(a) What is photo electric effect ? What are the main observations of photoelectric effect ?
(b) When a photon of frequency 1.0 X 10 15 S -1 was allowed to hit a metal surface ; an electron having
1.988 X 10 -19 J of kinetic energy was emitted. Calculate the threshold frequency of this metal. Show that
an electron will not be emitted if a photon with a wavelength equal to 600 nm hits this metal surface.
[2 + 3]

33. (i) What do you mean by successive electron gain enthalpies ? Why is the second electron gain enthalpy of
an atom positive ? Explain with example.
(ii) Define covalent radius. How does it vary in group &period ?
[3 + 2]

OR
(i) What are transition elements ? Why are they so called ? Write few properties of such elements.
(ii) What do you mean by diagonal relationship ? What is the cause for it ?

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