Goa Board Class 10 Question Paper Mar 2019 Science English

2019 IV 12 0930 Seat No.

Time : 2½ Hours SCIENCE (E)

Subject Code

S 0 3 1

Total No. of Questions : 5 (Printed Pages : 13) 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 main 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 complete statement : 1

(a) The alloy whose constituents are lead and tin is ..................

• Brass

• Bronze

• Solder

• Steel

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(b) All metals exists in same physical state except .....................

• Gold

• Mercury

• Aluminium

• Copper

(ii) Why is the brain contained in a fluid filled balloon ? 1

(iii) State any two abiotic factors of an ecosystem. 1

(iv) Observe the given diagram of action of steam on metal and

label ‘A’ and ‘B’ : 1

B
A

(B) (i) Answer the following : 2

(a) How does ozone affect any ecosystem ?

(b) Form a food chain from the following :

Fox, Grass, Rabbit, Tiger.

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(ii) Answer the following : 2

(a) Ores of many metals are found as oxides. Why ?

(b) Why is the reaction of iron oxide with aluminum used in
joining the railway tracks ?

(C) (i) Management of natural resources for sustainable development
is very essential : 2

(a) State the economic problem associated with the
construction of large dams.

(b) State any two effects of Chipko Movement.

(ii) Glands and Hormones play a vital role in living organisms : 3

Y

X

(a) Refer the diagram and identify the parts ‘X’ and ‘Y’.

(b) Why does the doctor advice insulin injections to a diabetic

patient ?

(c) When Adrenaline is secreted into the blood the breathing

rate increases. Why ?

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2. (A) (i) Select the correct alternative given below each statement and

write the completed statement : 1

(a) The slurry produced in a biogas plant is rich in ............

• Sodium and Chlorine

• Sodium and Fluorine

• Nitrogen and Oxygen

• Nitrogen and Phosphorous

(b) Silver is used in ..........................

• The preparation of solar cells

• The interconnection of solar cells in solar panels

• The supporting structure of solar panels.

• The solar cookers

(ii) What is the cause of refraction of light ? 1

(iii) Differentiate between principal focus of a concave mirror and

convex mirror. 1

(iv) A change that is useful for one property to start with, can

become useful later for a different function during evolution.

Give one example to support the statement. 1

(v) Name : 1

(a) Artificially selected vegetable having larger leaves.

(b) The earliest member of human species.

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(B) (i) Electricity is one of the important form of energy for all of
us. 2

(a) How can we generate electricity from hot springs ?

(b) State any two limitations in the use of wind energy.

(ii) Answer the following : 2

(a) What method is extensively used to define evolutionary
relationship ?

(b) With respect to size, distinguish between X and Y
chromosomes.

(C) Do as directed : 4

(i) Draw a neat ray diagram to show the formation of image by a
concave mirror when the object is placed ‘‘at C’’.

(ii) An object when placed at a distance of 25 cms from a convex
lens produces a double sized real image on the other side of
the lens. Calculate :

(a) The image distance

(b) The focal length of the lens.

OR

Do as directed : 4

(i) Draw a neat ray diagram to show the formation of image by
convex lens, when the object is placed ‘‘at 2F1’’.

(ii) (a) At what distance an object be placed in front of a concave
mirror so that a three times bigger real image is formed at
a distance of 60 cms from the mirror on the same side ?

(b) Find the focal length of above concave mirror.

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3. (A) (i) Match the formulae in Column ‘A’ with their appropriate names

in Column ‘B’ and rewrite the correct pairs : 1

Column A Column B

(a) C3H4 • Alcohol

(b) C6H14 • Alkyne

• Alkene

• Alkane

(ii) Show the formation of Covalent bond in oxygen molecule. 1

(iii) Watermelon flower cannot be self-pollinated ? Why ? 1

(iv) Male-Female sex ratio must be maintained in our society. Give

reason. 1

(B) (i) Do as directed : 2

(a) In Mendeleev’s periodic table, some elements with a

slightly greater atomic masses were placed before an

element with a slightly lower atomic mass. Illustrate with

an example.

(b) From the table given below find out which of the group
forms a Dobereiner triad. Why ?

Group I Atomic Group II Atomic

(Element) Mass (Element) Mass

A 14.0 X 40.1

B 31.0 Y 87.6

C 74.9 Z 137.3

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(ii) Answer the following : 2

(a) Ethanol is heated at 443° k with excess concentrated

sulphuric acid to give an unsaturated Hydrocarbon.

(1) Name the unsaturated hydrocarbon

(2) What is the role of concentrated sulphuric acid in

the above reaction ?

(b) Ethanoic acid belongs to a group of acid called carboxylic

acid.

(1) State the percentage of ethanoic acid in vinegar.

(2) Give the other name of ethanoic acid.

(C) The elements of the second period of the periodic table are given

below : 2

Group I II III IV V VI VII VIII

2nd Period P Q R S T

(i) Write the electronic configuration of element Q.

(ii) Which element is most metallic ?

(iii) Which element is inert gas ? Why ?

(D) Answer the following : 3

(i) Draw a neat diagram showing the Budding in Hydra (any one

stage) and label :

*Bud and *Tentacles.

(ii) State any two artificial methods of vegetative propagation in

plants.

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OR

(D) (i) Draw a neat diagram showing the germination of seed and

label : 3

*Cotyledon and *Plumule.

(ii) The fallopian tube in the female is blocked. How does this help

in avoiding pregnancy ?

4. (A) (i) Select the correct alternative given below each statement and

write the completed statement : 1

(a) A three carbon molecule formed from glucose during

Respiration in our body is ..............

• Lactic acid

• Acetic acid

• Ethanol

• Pyruvate

(b) Enzyme trypsin convert proteins into ...............

• Glycerol

• Amino acid

• Citric acid

• Starch

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(ii) State the role of blood platelets at the points of injury : 1

(iii) Pb + CuCl2 PbCl2 + Cu 1

(a) Identify the less reactive element in the above chemical

reaction.

(b) Name the above type of reaction.

(B) (i) Answer the following : 2

(a) Akbar was suffering from pain and irritation in the

stomach.

What is the cause of pain and irritation in the

stomach ?

(b) The pH of lemon juice and pure water are

approximately 2 and 7 respectively.

State the change in colour of litmus paper when dipped

in the above two solutions.

(ii) Do as directed : 2

(a) With respect to hydrogen, differentiate beween oxidation

and reduction.

(b) Why is it necessary to balance the chemical equation ?

(iii) Answer the following : 2

(a) Blue Copper Sulphate crystals when heated turn white.

Give scientific reason.

(b) Why does Plaster of Paris become hard on mixing with

water ?

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(C) Do as directed : 4
(i) Draw a neat diagram showing the stages of nutrition in Amoeba
and label :

*Food Vacuole and *Pseudopodia.
(ii) Name :

(a) A plant parasite

(b) Filtration units in the kidney.
(iii) Carbon dioxide is transported in dissolved form in our blood.
Give reasons.

5. (A) (i) Select the most correct alternative given below each statement
and write the completed statement : 1
(a) The far point of a normal eye in human being is ................

• 25 cms

• 250 cms
• Infinity

• 2.5 cms
(b) The apparent flattening of sun’s disc at sunrise and
sunset is due to ..........................

• Dispersion of light
• Atmospheric refraction

• Tyndall effect
• Scattering of light
(ii) Write the function of rheostat in an electric circuit. 1

(iii) State one most convenient method of inducing a current in a
coil. 1

(iv) A shop in the market was burnt due to fluctuations in supply
voltage. Write any two causes. 1

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(B) Answer the following : 2

(i) State any two ways that can enhance the power of commercial
motor.

(ii) Observe the figure given below and answer the following :

(a) What do concentric circles represent ?

(b) What will happen if the current through the conductor
is decreased ?

(C) Human eye is the most significant part as it enable us to see the
colourful world around us. 3

(i) What is the colour of the sky when viewed from the earth ?

(ii) State one example of a natural spectrum.

(iii) Why are danger signals red in colour ?

(iv) When you are looking at objects closer to the eye, what would
be the effect on :

(a) Ciliary muscles

(b) Curvature of eyelens.

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OR

(C) Anupa can see a parrot sitting on a tall coconut tree but cannot read

the printed matter from the newspaper clearly. 3

(i) Write the cause of the above effect with respect to (a) Focal

length (b) Size of the eyeball.

(ii) What is the role of light sensitive cells on the retina of the

eye ?

(iii) The peculiar shape of the prism makes the emergent ray bend

at an angle to the direction of incident ray :

(a) What is the angle formed between the incident ray and

the emergent ray called ?

(b) Which colour of spectrum of light produced by prim bends

the most ?

(D) Attempt the following : 4

(i) Observe the circuit diagram and answer :

R1(9 )

R2(9 )

R3(9 )
K

+ –
A
R4(1 )
20 V

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Calculate :

(a) Total resistance across R1, R2 and R3
(b) Total resistance across the circuit
(c) Total current in the circuit.
(ii) How does the resistance depend on the area of cross section of
a conductor ?
(iii) To verify Ohm’s Law V-I graph is a straight line that passes
through the origin. What does this indicate ?
OR
(D) (i) Observe the circuit diagram and answer : 4

Conductor Lamp
50
10
(I = 0.20A)
K
– +
A

Calculate :

(a) Potential difference across the lamp and the conductor.

(b) Power of the circuit.

(ii) How does the resistance depend on the length of a conductor ?

(iii) Why are alloys used in the electric devices like electric iron ?

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