Subject : SCIENCE Time : 3 hrs. 15 minutes English Medium: Regular Fresh 2020-21 Subject Code : 83E Max. Marks:80

Part-A

Physics

A)Four alternatives are given for  each of the following questions/incomplete statements. Choose the correct alternative  and write the complete  answer along with its letter  of alphabet     4×1=4

A)The quality of environment can be improved by

a)deforestation

b)over use of fossil fuel

c)erosion

d)conservation

2)S. I unit of resistivity

a)ohm

b)ohm meter

c)columb

d)volt

3)which device produces electric current?

a)generator

b)galvanometer

c)ammeter

d)resistor

B]Answer the following   2×1=2

4)state flemings right hand rule

5)"The refractive index of diamond is 2.42”. What is the meaning of this statement in relation to speed

C]Answer the following   3×2=6

6)Suggest three ways to maintain a balance between environment and development to survive. 

7)Draw a neat labelled diagram of electric motor

8) What are the limitations of the energy m can be obtained from the oceans?

D]Answer the following  3×3=9

9)Write two points of difference between electric energy and electric power. (b) Out of 60 W and 40 W lamps, which one has higher electrical resistance when in use.

                 Or

a)Define 1 dioptre of power of a lens.

b)Find the focal length of a convex mirror whose radius of curvature is 32 cm.

10)At what distance should an object be placed from a convex lens of focal length 18 cm to obtain an image at 24 cm from it on the other side. What will be the magnification produced in this case?

11)why can wind energy forms be established only at specific location give reason to support to your answer

E]Answer the following  2×4=8

12)What is electromagnetic induction? Explain how the movement of a magnet towards or away from a coil carrying a galvanometer produce current? Write the rule to find the direction of current in this above coil.

                   Or

a)Why do we prefer a convex mirror as a rear-view mirror in vehicles?

b)state the joules law of heating effect

F]Answer the following    5×1=5

13)are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption ?   

Part -B

Chemistry

G]Four alternatives are given for  each of the following questions/incomplete statements. Choose the correct alternative  and write the complete  answer along with its letter  of alphabet       2×1=2

14) functional group ofcarboxylic acid

a)-OH

b)-CHO

c)-COOH

d)none

15)What is the pH range of our body?

(a) 7.0 – 7.8

(b) 7.2 – 8.0

(c) 7.0 – 8.4

(d) 7.2 – 8.4

H]Answer the following 4×1=4

16)what is weak acid?

17)State newlands laws of octaves

18)What is an additional reaction?

19)Arrange the following metals in the decreasing order of reactivity Na, K, Cu, Ag.

I]Answer the following 2×3=6

20)Among CH4, C2H6 and C4H10 which is expected to show isomerism?

21)The atomic numbers of three elements X, Y and Z are 3, 11 and 17 respectively. State giving reason which two elements will show similar chemical properties.

or

The pH of three solutions A, B and C are 4, 9 and 6 respectively. Arrange them in increasing order of acidic strength.

22)what is the composition of molten slag, formed in the extraction of iron in the blast furnace?

ii) What is the use of slag?

J]Answer the following 3×3=9

23)Draw the diagram of the arrangement  of the apparatus  showing the reaction  of  zinc granules with dilute sulphuric acid and testing hydrogen gas by burning. Label the following parts : (i) Zinc  granules (ii)  Delivery  tube

24)a)How are the molecules of aldehyde and Ketone structurally different?

b)what is catenation

Or

25)Explain cleansing action of soap

26)Give reasons for the following

i) Zinc oxide is considered an amphoteric oxide.

ii) Non-metals in general do not displace hydrogen from dilute acids.

K]Answer  the following question.                1 x 4=4

26) a)  Explain the formation of the  ionic  compound sodium chloride  with the help of electron dot structure.

b)How do you test ammonia gas

Part-c

Biology

L)Answer the following 2×1=2

27)The constituents which do not form eco-system are

  I.  Biotic constituents

 II.  Plastic bags

 III.  Abiotic constituents

  IV.  All of these

28)Fall of mature leaves and fruits from plants is triggered by which of the following substance?

(a) Auxin

(b) Cytokinin

(c) Gibberellin

(d) Abscisic acid

M)Answer the following 2×1=2

29)How is the increase in demand for energy affecting our environment adversely?

30)what is rain harvesting

N)Answer the following 3×2=6

31)How is oxygen  rich  blood  from  the  lungs supplied  to  all  the  cells  in  the  human body?

OR

What are the raw materials used during photosynthesis? Write chemical equation for photosynthesis.

32)State an instance where human intervention saved the forests from destruction.

33)Draw a neat labelled diagram of structual and functional unit of brain

O)Answer the following      3×3=9

34)How is sex determined in human beings?

                    OR

How do homologous organs provide evidence in support of evolution?

35 )What are the male and the female gonads in the human beings? Mention their functions.

               OR

a)what is the effect of DNA copying which is not perfectly accurate on the reproduction process?

b)define double fertilization

36)Draw a neat labelled diagram of the cross section of the human brain.. Label the following parts

a)largest part of brain

b)balancing posture of the body

P]Answer the following   2×4=8

37)Explain with the help of a suitable example where the colour change gives no survival advantage to a species.

38)a)Which part of the brain controls involuntary actions? Write the function of any two regions of it.

b)What are ‘hormones’? State one function of each of the following hormones:

(i) Thyroxine (ii) Insulin