Goa Board Class 10 Question Paper Apr 2018 Science English

2018 IV 11 0930 Seat No. :

Time : 2½ Hours SCIENCE (E)

Subject Code

S 0 3 1

Total No. of Questions : 5 (Printed Pages : 8) Maximum Marks : 65

INSTRUCTIONS : i) The question paper consists of five questions of 13 marks each.
ii) All questions are compulsory.
iii) There is no overall choice, however internal choice has
been provided in two questions of three marks and two
questions of four marks category. You have to attempt
only one option in such questions.
iv) Begin each question on a fresh page.
v) Figures to the right indicate full marks.
1. A) i) Select the correct alternative from those given below each statement
and write the completed statement : [1]
a) Aluminium is obtained by the electrolytic reduction of ___________
• Aluminium sulphide
• Aluminium oxide
• Aluminium carbonate
• Aluminium nitrate
b) Iodine is a non-metal and it is __________
• Malleable
• Ductile
• Sonorous
• Lustrous
ii) Name the following : [1]
a) Receptors that detect taste.
b) Hormone that regulates the growth and development in human beings.
iii) Write one harmful effect of ultra violet radiations in human being. [1]
iv) Why should we not throw small pieces of sodium into a laboratory sink ? [1]
B) i) a) Given below are some organisms. Arrange all of them in a food
chain and show the direction of flow of energy. [2]
Eagle, grasshopper, frog, grass, snake.

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b) Which of the organism in the above food chain has maximum amount
of energy ?
c) Give an example of artificial ecosystem.
ii) An environmentalist on a visit to your school suggested various
methods to save the environment. [2]
a) What does the term ‘Reduce’ refer to ?
b) List any two advantages of water harvesting.
iii) Answer the following : [2]
a) How do we extract metals low in activity series from their ores ?
b) What is anode mud ?
C) i) David and Debbie were riding a bike without helmets and met with an
accident.
Observe the diagram of the human brain and identify the part of brain
marked A, B or C affected in the following cases. [1]

a) Debbie had an instant death.
b) David lost all his memory and ability to think.
ii) What happens at the synapse between two neurons ? [1]
iii) Why is it advisable to have iodized salt in our diet ? [1]
2. A) i) Select the correct alternative from those given below each statement
and write the completed statement : [1]
a) Brown fumes emitted when lead nitrate is heated are of __________
• Nitrogen dioxide
• Lead oxide
• Lead
• Nitric acid
b) Respiration is an example of ______________
• Exothermic reaction
• Endothermic reaction
• Displacement reaction
• Precipitation reaction

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ii) Name the following : [1]
a) The first enzyme to mix with food in the digestive tract.
b) The smallest blood vessels with one cell thick walls.
iii) Answer the following : [2]
a) Calcium compound having an odour of chlorine is used to remove
yellowness of white clothes in laundries. Name the compound.
b) Write the formula of a salt that contains water of crystallization.
c) On what does the strength of a base depend ?
B) i) Translate the following statement into chemical equation : [2]
a) Hydrogen sulphide gas burns in air to give water and sulphur dioxide.
b) Balance the above equation.
ii) Answer the following : [2]
a) How are alveoli designed to maximise the exchange of gases ?
b) Write a point of difference between parasites and saprophytes.
iii) Explain the following giving reasons : [2]
a) Why does tooth decay start when the pH of the mouth is lower than 5.5 ?
b) Plaster of Paris is utilized in making cast for broken limbs in hospitals.
C) i) Draw the diagram of open and closed stomata and label : [3]
a) chloroplast
b) guard cells.
ii) What is the source of oxygen produced during photosynthesis ?
iii) In which form are Carbohydrate stored in plants ?
OR
C) i) Draw the diagram of human excretory system and label : [3]
a) urinary bladder
b) urethra.
ii) Name two major components of normal human urine.
3. A) i) Match the following : [1]
a) Eka-Boron – Gallium
b) Eka-silicon – Scandium
– Germanium
ii) Identify and name the following compounds : [1]
a) CH3CH2CHO
b) CH3 − C − CH2 − CH3 .
||
O

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iii) Why do variations arise in progeny during sexual reproduction ? [1]
iv) State two demerits of Mendeleev’s classification of elements. [1]
v) Answer the following : [2]
a) State two characteristic features of carbon which when put together
give rise to large number of carbon compounds.
b) Give a point of difference between soaps and detergents.
B) i) The following table shows the position of six elements A, B, C, D, E
and F in the modern periodic table : [2]
Group ⇒
Period 1 2 3 / 12 13 14 15 16 17 18
⇓
2 A B C
3 D E F
a) Which element is a metal with valency 2 ?
b) Which element is a non-metal with valency 3 ?
c) Out of D and E which one has a bigger atomic radius and why ?
ii) Study the equations and answer the following : [1]
a) CH3CH2OH ⎯⎯ acidic K 2Cr2O 7
⎯ ⎯ ⎯ ⎯ ⎯⎯→ CH3COOH
What is the role of K2Cr2O7 in the above reaction ?
hot con
b) CH3CH2OH ⎯⎯ ⎯ ⎯ ⎯→ CH2 = CH2 + CHO
H2SO 4
What is the role of H2SO4 in the above reaction ?
C) Reproducing organisms create new individuals that look very much
like themselves. [4]
i) Observe the diagram given below and answer the question :

What is the function of parts marked A and B ?

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ii) What could be the reason for adopting contraceptive methods ?
iii) Write a point of difference between pollination and fertilization.
iv) Name the following :
a) The terminal sticky part of the carpel.
b) The mode of reproduction in yeast.
OR
C) The modes by which organisms reproduce depend on the body design
of the organisms. [4]
i) Observe the diagram given below and answer the questions :

What is the role of the part marked ‘A’ ?
ii) Why does menstruation occur ?
iii) Write a point of difference between a male gamete and a female gamete ?
iv) Name :
a) The organism in which binary fission occurs in definite orientation
b) The structure where spores are formed in rhizopus.
4. A) i) Select the correct alternative from those given below each statement
and write the completed statement : [1]
a) In Mendel’s breeding crosses, F2 generation was produced through
___________
• Cross breeding of F1 individuals
• Self pollination of F1 individuals
• Cross breeding one of individual and the parents
• Self fertilization of one of all parent
b) In some animals like snails sex determination is regulated by _______
• Male gamete
• Both male and female gamete
• Female gamete
• Environmental cues
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ii) Name the following : [1]
a) The energy produced due to the temperature difference in a sea level.
b) The residue left behind when wood is burnt in limited supply of air.
iii) What factors could lead to the rise of new species ? [1]
B) i) Inspite of the high cost and low efficiency solar cells are used in many
applications. [2]
a) What is the range in voltage produced in a typical solar cell ?
b) Why are solar panels mounted on specially inclined rooftops ?
ii) Answer the following : [2]
a) Why do all gametes formed in females have only X chromosomes ?
b) Which process can be illustrated by the example of evolution of broccoli
from wild cabbage ?
c) What will be the ratio in F2 generation in Mendels dihybrid cross ?
iii) Observe the following diagram and answer the question given below : [1]

Explain why a ray of light passing through the centre of curvature of a
concave mirror gets reflected back along the same path.
iv) Why does the light ray incident in a rectangular glass slab emerge
parallel to incident ray ? [1]
C) Do as directed : [4]
i) Draw a ray diagram to show the formation of an image when an object
is placed between F and P of a concave mirror.
ii) A needle placed 45 cm from a convex lens, forms an image on a
screen placed 90 cm on the other side of a lens. Determine its focal
length. What is the size of the image if the object is 5 cm ?
OR
C) Do as directed : [4]
i) Draw a ray diagram to show the formation of an image when an object
is placed between focus (F1) and optical centre (O) of a convex lens.
ii) A concave mirror produces 3 times enlarged image of an object placed
10 cm in front of it. Calculate its radius of curvature.

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5. A) i) Select the correct alternative from those given below each statement
and write the completed statement : [1]
a) The part of eye that regulates and controls the amount of light entering
the eye is __________
• Retina
• Pupil
• Iris
• Cornea
b) The phenomenon of scattering of light by colloidal particles is called ______
• Reflection
• Refraction
• Tyndal effect
• Deflection
ii) Observe the correlation in the first pair and complete the second pair : [1]
1 Joule
a) 1 volt = :: 1 ohm = _____________
1 Coulomb

b) Resistor of resistance : :: Rheostat : _________________
iii) Name two safety measures commonly used in domestic electric
circuit and appliances. [1]
iv) Answer the following : [1]
a) Name the rule used to find the direction of induced current in a
conductor moving in a magnetic field.
b) What is the frequency of household alternating current (AC) in India ?
B) Electricity and magnetism are linked to each other. [2]
i) Why does a current carrying solenoid when suspended freely rest
along a north south direction ?
ii) Two fuse wires A and B of the same length but rated 20 A and 10 A
respectively which will be more thicker and why ?
C) Ramu’s eye lens has an excessive curvature. [3]
i) Where is the image of the distant object formed in Ramu’s eyes ?
ii) Bifocal lenses consists of concave and convex lenses respectively. Why ?
iii) Why we cannot read a printed page by holding very close to our eyes ?
OR
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C) The human eye is one of the most valuable and sensitive sense organ.
It enables us to see wonderful world of colors. [3]
i) Why does the sky appear dark from the moon ?
ii) Write two effects of atmospheric refraction.
iii) Write a point of difference between dispersion and spectrum.
D) Do as directed : [4]
i) Draw a circuit diagram for verifying Ohm’s law. Connect a resistor,
an ammeter, a plug key, a battery and a voltmeter across the resistor.
Show the direction of the flow of current.
ii) Find out the following from the electric circuit given below :

a) Total resistance of resistors in the above combination.
b) Amount of current flowing through the circuit.
_____________________

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