Science PQ2
Science PQ2
Science PQ2
Class X
Science (Subject Code – 086)
Section-A
Select and write the most appropriate option out of the four options given for each of the
questions 1 - 20. There is no negative mark for an incorrect response.
Q. Questions Mark COMP.
Nos
1 1 U
4 The metal X does not react with cold water but floats on hot 1 U
water with formation of colourless bubbles. Which of the
following represents metal X.
a) Aluminium
b) Copper
c) Magnesium
d) Lead
5 1 U
Gas
X
.
a. In which of the test tubes she will observe the reaction
to be most vigorous
b. What is the reason for her observation?
c. Write a well-balanced equation of the reaction in (b)
Section-D
Question No. 34 to 36 are long answer questions.
34 An organic compound ‘P’ is a constituent of wines. ‘P’ on 1x5 A
reacting with acidified K2Cr2O7 forms another compound ‘Q’.
When a piece of sodium is added to ‘Q’, a gas ‘R’ evolves
which burns with a pop sound when a burning matchstick is
brought near it.
a) Give the chemical name of compound P.
b) Mention another use of the compound ‘P’ apart from the
use mentioned in the question.
c) Illustrate with the help of chemical equation the
conversion of ‘P’ into ‘Q’.
d) Give a balanced equation to depict the reaction of Q
with sodium.
e) What happens when ‘P’ is heated with conc. H2SO4 at
443 K, write its chemical equation.
OR
An organic compound ‘X’ is a liquid at room temperature. It is
also a very good solvent and has the molecular formula C2 H6
O. Upon oxidation ‘X’ gives ‘Y’. ‘Y’ releases a gas ‘W’ with brisk
effervescence on reacting with NaHCO3. X reacts with Y in the
presence of conc.H2SO4to give another compound ‘Z’ which
has a pleasant smell. Z.
a) Give the chemical name and chemical formula of Y.
b) How will you test for the gas ‘W’?
c) Depict the formation Y and Z using chemical equations.
d) Name the reaction of formation of ‘Z’.
e) Give any one use of ‘Z’?
35 a) Flow of energy in a food chain is unidirectional. Justify the 2+3
statement.
b)
i) In a cross between pea plants having round green seeds
and wrinkled yellow seeds, what progeny is expected in
F1 and F2 generation?
ii) What would be the impact on the ratio of F2 generation, if
F1 progeny plants inherited a single whole gene set from
each parent? Give reason for your answer.
OR
a) How does blood sugar level get regulated in the human
body?
b)
i) Which hormone is secreted into the blood when you are
under stress? Name the gland that secretes this
hormone.
ii) How does it help the body to cope up in an emergency
situation?
36 A person is unable to see objects distinctly placed within 75 cm 1+2+2 AP
from his eyes.
a) Name the defect of vision the person is suffering from.
b) List its two possible causes.
c) Calculate the power of the lens needed to correct this
defect. Assume that the near point for the normal eye is
25 cm.
OR
a) Why is a normal eye not able to see clearly the objects
placed closer than 25 cm?
b) With the help of a diagram show recombination of the
spectrum of white light.
c) List two essential conditions for observing a rainbow.
SECTION - E
Question No. 37 to 39 are case-based/data -based questions with 2 to 3 short sub-
parts. Internal choice is provided in one of these sub-parts.
37 Give any two uses of pH in everyday life other than mentioned 1+1+2 U
Give any two uses of pH in everyday life other than mentioned
in the context.
In the diagram given below when electricity is passed through
an aqueous solution of a common salt, A substance ‘Z’ is
produced along with the evolution of gases ‘X’ and ‘Y’. When
a burning matchstick is brought near the gas ‘Y’ it burns with a
pop sound, whereas X is used for disinfecting drinking water.
When gas ‘X’ is passed through a solution of slaked lime, an
insoluble substance ‘A’ is produced.
a) Write the name of gases ‘X’ and ‘Y’.
b) Write the balanced chemical equation for the formation
of substance ‘A’.
c) Write you observations:
i) if a drop of blue litmus solution is added to the
aqueous solution of substance ‘Z’
ii) if methyl orange is added to substance ‘Z’
OR
Write a balanced chemical reaction that takes place when ‘X’
and ‘Y’ react with each other. The product so produced will turn
blue litmus red only when wet, why?
38 1+1+2
OR
c) Define resistivity. What are the factors affecting the
resistivity of a conductor?