PRINCE SRIVARI SENIOR SECONDARY SCHOOLS

MADIPAKKAM & NANGANALLUR

HALF YEARLY ONLINE EXAMINATION - DECEMBER 2020
X Std SCIENCE Marks : 100
Time : 3.00hrs
PHYSICS
Section A (8x1=8)
1. Why does the sun appear white at noon? (1)
2. Write SI unit of resistivity (1)
3. Name the type of current (1)
a) Used in household supply b) given by a cell
For question numbers 4 & 5 two statements are given one labeled Assertion
(A) and other labeled Reason (R). Select the correct answer to these question
from the codes a,b,c&d given below.
a) Both A and R are true and R is correct explanation of the assertion.
b) Both A and R are true but R is not the correct explanation of the
assertion.
c) A is true, but R is false.
d) A is false but R is true.
4. Assertion (A). In a series circuit, the current is constant throughout the
electric circuit.
Reason (R):-All electric devices need equal currents to operate properly.(1)
5. Assertion (A):- Incident ray is directed towards the centre of curvature of
spherical mirror. After reflection if retraces its path
Reason (R): Angle of incidence i = Angle of reflection r=0 (1)
Answer question number 6,7 & 8 based on your understanding of the
following paragraph and the related studied concepts.
6. When light falls on the prism, it splits its incident light into a band of
colours. The sequence of colours observed is VIBGYOR. This band of
colour is known as spectrum. So this splitting of incident light into
different colours is known as dispersion. The splitting in due to the
bending of light rays at different angles (3)
 a) Which colour has the highest wavelength?
b) Which colour has the highest velocity?
c) Which colour has the highest refractive index?
Section – B (3x2=6)
7. Study the following electric circuit and
find (i) the current flowing in the circuit and
(ii) the potential difference across 10Ω resistor (2)

or
 Find the current drawn from the battery by the network of four
resistors shown in the figure.
8. State the two laws of reflection of light (2)
9. The given magnet in divided into three parts A, B and C
A B C
Name the parts where the strength of the magnetic field in (i)
maximum (ii) minimum. How will the density of magnetic field line
differ at these parts? (2)
Section - C (3x3=9)
10.What is meant by solenoid? How does a current carrying solenoid
behave? Give its main use. (3)
11.When and where do we see a rainbow? How is a rainbow formed?
Draw a labeled diagram to illustrate the formation of a rainbow (3)
12.If the image formed by mirror for all positions of the object placed
infront of it is always virtual and diminished, State the type of the
mirror. Draw a ray diagram in support of your answer. Where are
such mirrors commonly used and why? (3)
(or)
The absolute refractive indices of glass and water are 3/2 and 4/3
respectively. If the speed of light in glass is 2x108m/s. Calculate the
speed of light is (i) Vacuum (ii) Water
Section – D (2x5=10)
13.One half of a convex lens of focal length 10cm is covered with a black
paper. Can such a lens produce an image of a complete object placed
at a distance of 30 cm from the lens? Draw a ray diagram to justify
your answer.
A 4cm tall object is placed perpendicular to the principal axis of a
convex lens of focal length 20 cm. The distance of the object from the
lens is 15cm. Find the nature, position and size of the image (5)
(or)
What is meant by power of a lens? Define its SI unit.
You have two lenses A and B of focal length +10cm and -10cm
respectively. State the nature and power of each lens which of the
two lenses will form a virtual and magnified image of an object
 placed 8 cm from the lens? Draw a ray diagram to justify your
answer.
14.State Ohm’s law. Write the necessary conditions for its validity. How
is this law verified experimentally? What will be the nature of graph
between potential difference and current for a conductor? Name the
physical quantity that can be obtained from this graph (5)
(or)
Two wires A& B are of equal length and have equal resistance. If the
resistivity of A is more than that of B which wire is thicker and why?
For the Electric circuit give below calculate.
(i) Current in each resistor
(ii) Total current drawn from the battery
(iii) Equivalent resistance of the circuit.
 CHEMISTRY
I. Answer the following as directed:
Choose the correct answer (7x1=7)
1. Fe2o3 +2Al  2 Fe + Al2 O3
a) Aluminium is an oxidizing agent.
b) Aluminium gets reduced to Aluminium oxide.
c) Iron oxide is getting reduced to iron.
d) Aluminium oxide is acting as a reducing agent.
2. Pick out the acidic salt from the given below
a) CuSO4 b) Nacl c) K2 CO3 d) Na2CO3
3. Diamond is not a good conductor of electricity because
a) It is very hard.
b) It has no free electrons.
c) It is water soluble.
d) None of the above.
4. Name the metals present in third period and metalloid in the same
period.
5. Define thermal decomposition reaction with an example.
6. Name the gas evolved when acid reacts with zinc metal and write a
test for evolved gas.
7. Assertion (A): Aqueous Ammonia is a base
-
Reason (R): It does not contain oH ions
Pick out the correct option:
a) A and R are correct. R explains A
b) A is true and R is false
c) A is false and R is true.
d) Both A and R are false.

II. Read the passage and answer the questions given below (4x1=4)

A compound “X” is a white powder which is a constituent of baking powder

and used in some antacids. When heated it gives a compound “Y” which is
anhydrous and absorbs water to become hydrated salt, When kept open in air
“Y” lose water molecules when “Y” dissolves in water it forms a strong base
and weak acid “Z”.
 1. a) What is the nature of solution formed by dissolving “Y” in water.
b) Identify X, Y and Z with chemical formula
c) Write the constituent of baking powder.
d) What happens when baking soda is heated strongly?

III. Answer the following questions:

1. State Modern periodic law. Write the position of an element with atomic
number 15 in modern periodic table (2)
2. Reddish brown metal “M” reacts with oxygen to form metallic oxide MO.
This oxide reacts with moisture and carbon-di-oxide to form basic
carbonate which can prevent rusting of iron. Identify the metal and also
write the chemical reaction that place. (2)
3. Taking a suitable example show the formation of a molecule formed by
triple covalent bond. (3)
4. Silver gets tarnished, Write the chemical reaction that takes place, what
is meant by corrosion? (3)
5. When you mix the solution of lead (II) nitrate and potassium Iodide.
a) What are the products formed?
b) What is the colour of precipitate formed in the above reaction. Name
the compound.
c) Write the balanced equation for the above.
d) Name the kind of chemical reaction that takes place.
(or)

ii) Read the table given below and Answer the following questions. (3)

Element Atomic number

A 3
B 17
C 13
D 11
a) How many valence electrons are three in “C” and find its valency.
b) Name the compound formed between A and B
c) The compound AB will conduct electricity or not. If so give reason.
IV) Answer in detail (any two) (2x5=10)

1. What is homologous series? What are the characteristic properties of

homologous series? (5)
2. a) What is Brine solution? What are the products formed when
electricity is passed through brine solution?
(1)
b) Name the gas that evolved at the anode and cathode? (1)
c) Write the uses of sodium hydroxide and chlorine gas. (2)
d) Write the chemical reaction that takes place when brine solution
is electrolysed.
(1)
3. Complete the following reaction and then balance the chemical reaction.
a) Aluminium with sulphuric acid. (1)
b) Green vitriol on heating strongly. (1)
c) Iron with Steam (1)
d) Silver nitrate with common salt (1)
e) Slaked lime with chlorine gas (1)
 BIOLOGY
SECTION – A (6X1=6)
1. Write the equation of photosynthesis. 1
2. Define peristalsis 1
3. The breakdown of pyruvate to give carbon-di-oxide, water and energy
takes place in 1
a) Cytoplasm b) Mitochondria c) Chloroplast d) Nucleus.
4. We do not clean ponds or lakes, but an aquarium needs to be cleaned.
Why? 1
5. Which of the following is not a part of the reproductive system in human
beings? 1
a) Ovary b) Vas deferens c) Fallopian tube d) Uterus.
6. Who is the “Father of Genetics”? 1
SECTION – B (1X1=1)
7. In the following question, a statement of Assertion is given below
followed by a corresponding reason. Read the following question and
choose the correct answer.
a) Both (A) and (R) are true and (R) is the correct explanation of the
Assertion (A)
b) Both (A) and (R) are true but (R) is not the correct explanation of the
assertion (A)
c) (A) is true, but (R) is false.
d) (A) is false, but (R) is true.

Assertion (A): The sex of a child in human beings will be determined

by the type of chromosome he / she inherits from the
father
Reason (R) : A child who inherits ‘X’ Chromosome from father would
be a girl (XX), while a child who inherits a ‘Y’
chromosome from the father would be a boy (XY)

SECTION – C (4 X 1 = 4)
8. Neeraj, class IX student is extremely fond of chocolates and junk food.
He often complains about the pain in his teeth and fails to attend the
school many times due to which he was lacking in his studies too.
Teacher rang up his father and advised him to take him to the dentist.
 His father when visited the dentist, he after examining suggested that
Neeraj is suffering from tooth decay and advised him to leave all
unhealthy and outside food.
1. What do you know about the term tooth decay?
2. How does tooth decay occurs?
3. Suggest any one treatment for it.
4. What values should Neeraj incorporate in himself for good health of
his teeth?
SECTION – D (2X2=4)
9. Why is it necessary to separate oxygenated and deoxygenated blood in
Mammals and Birds? (2)
10.What are contrasting characters? Tabulate them as observed by the
geneticist in Pea plants (2)
SECTION – E (3X3=9)
11.Calculate the percentage of energy that will be available to big fish in the
following food chain.
Algae Zooplankton  Fish  Big Fish.
The energy available to algae from the sun is 10000J (3)
12.What is placenta? Mention its role during pregnancy. (3)
13.What are the differences between the transport of materials in xylem
and phloem?
(or)
Why is diffusion insufficient to meet the oxygen requirements of
multicellular organisms like humans? (3)
SECTION – F (2X5=10)
14.Draw and label Vertical section of Human Heart. (5)
(or)
Explain the stages of nutrition in an Amoeba with a neat diagram
15.a) What is ozone? How does it affect any ecosystem?
b) List down the problems caused by the non-biodegradable wastes that
we generate? (5)
(or)
Draw and label : Longitudinal section of a flower.
******