MG SCHOOL EDUCATION: SSLC Science Annual exam 2022 answer

SSLC Science Annual exam 2022 answer

I 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. 4x1=3

1. The device used to produce electricity is

A) Galvanometer B) Electric generator

C) Ammeter D) Electric motor

Ans: B) Electric generator

2. the correct formula that shows the relationship between potential difference, electric current and resistance is an electric circuit is

A) I = R/V B) I= VR

C) V= I/R D) R= V/R

Ans: D) R= V/R

3. In Fleming's right hand rule, the middle finger indicates the direction of

A) induced electric current B) magnetic field

C) motion of the conductor D) mechanical force

Ans: A) induced electric current

4. To get diminished and real image of an object from a convex lens, the object should be placed

A) at principal focus F1

B) between principal focus F1 and 2F1

C) beyond 2F1

D) between principal focus F1 and optical center O

Ans: C) beyond 2F1

II . Answer the following questions. 2x1=2

5. magnetic field lines do not intersect each other. Why?

Ans: Two magnetic field lines do not intersect each other because if there was point of intersection, The compass needle would point towards 2 directions which is not possible.

6. Mention the SI unit of power of lens.

Ans: Dioptre is the SI unit for measuring the power of a lens.

III. Answer the following questions. 3x2=6

7. Draw the schematic diagram of an electric circuit comprising of electric cell, electric bulb, ammeter and plug key.

Ans:

8. An object is placed at 25cm in front of a concave mirror of focal length 15 cm. At what distance from the mirror a screen be placed in order to obtain a sharp image?

Ans:

Object-distance, u = – 25.0 cm;

Focal length, f = –15.0 cm;

Image distance, v = ?

1/v + 1/u = 1/f

1/v = 1/f - 1/u

1/v = 1/(-15) - 1/ (-25)

1/v = -1/15 + 1/25

1/v = -5+3/75

1/v = -2/75

v= -37.5cm

A concave lens has focal length of 15 cm. At what distance should the object from the lens be placed so that it forms an image at 10 cm from the lens?

Ans:

A concave lens always forms a virtual, erect image on the same side of the object.

Image distance v = –10 cm;

Focal length f = –15 cm;

Object distance u = ?

1/v - 1/u = 1/f

-1/u = 1/f - 1/v

1/u = 1/v - 1/f

1/u = 1/(-10) - 1/(-15)

1/u = -1/10 + 1/15

1/u = -3+2/ 30

1/u = -1/30

u = -30cm

the object-distance is 30 cm.

IV. Answer the following questions. 3x3=9

9. which is the major component of biogas? write four characteristics of a good sources of energy.

Ans:

the major component of biogas is methane

It should be a sustainable and renewable source of energy.
It should have a high calorific value.
It should be easily accessible and provide energy for the maximum period of time.
It should not cause pollution.

which element is used in making solar cell? Write any four advantages of solar cells.

Ans:

Silicon / Si

The advantages of solar cells :

They have no moving parts
Little maintenance
Work quite satisfactorily without the use of any focusing device
Can be set up in remote areas where people cannot reach easily
Can set up in those areas too, where laying of power transmission line is not possible. ( Any four )

10. Draw the ray diagram to show the image formation by a convex lens, when the object is kept at 2F1 of the lens. With the help of the ray diagram mention the position and nature of the image formed. [ F1 : Principal focus of the lens ]

Ans:

Position of the image — At 2F 2

Nature of the image — Real and inverted

11. What are the functions of an earth wire ? It is necessary to connect the electric appliances having metallic body to earth wire in domestic electric circuit. Why ? Explain.

Explain Faraday’s experiment related to electromagnetic induction. Mention the difference between direct and alternate current.

Ans. :

Functions of the earth wire :

This is used as a safety measure for appliances have metallic body in domestic circuit
This provides a low resistance conducting path for the current
Any leakage of current in the appliances keeps its potential to that of the earth and the user may not get a severe electric shock.

Take a coil of copper wire having a large number of turns connect the ends of the coil to a galvanometer
Take a strong magnet and move its one pole into the coil
There is a deflection in the needle of the galvanometer. This indicates the presence of a current in the coil
Likewise, when the magnet is withdrawn back then also the needle of galvanometer deflects and this indicates the presence of electric current.

Direct Current: Direct current flows in one direction

Alternating current: Periodically alternating current reverse its direction

V. Answer the following question : 1 × 4 = 4

12. a) What are the advantages of connecting electrical devices in parallel in an electric circuit instead of connecting them in series ?

b) How are ammeter and voltmeter connected in an electric circuit ? What are their function ?

Ans. : a) Advantages of connecting electrical devices in parallel are :

The parallel circuit divides current through the electrical gadgets.
When one component fails, the circuit does not fail
The total resistance in parallel circuit decreases, so that
Electrical gadgets get current as per their resistance required. ( Any two )

In an electrical circuit ammeter is connected in series
In an electrical circuit voltmeter is connected in parallel
Ammeter measures the rate of electric current in a circuit
Voltmeter measures the potential difference across the ends of a conductor 2

VI. Answer the following question : 1 × 5 = 5

13. a) What is refraction of light ? State two laws of refraction of light.

b) What is refractive index of light ? “The refractive index of diamond is 2·42.” What is the meaning of this statement ?

Ans. :

Light travelling obliquely from one medium to another, the direction of propagation of light in the second medium changes
The incident ray, the refracted ray and the normal to the interface of two transparent media at the point of incidence all lie in the same plane
The ratio of sine of angle of incidence to the sine of angle of refraction is constant, for the light of given colour and for the given pair of media / sini / sinr = constant

b) The ratio of speed of light in air and the speed of light in medium. The ratio of speed of light in air and the speed of light in diamond is 2·42.

PART - B ( CHEMISTRY )

VII. Multiple Choice : 2 × 1 = 2

14. The gas liberated at the cathode in the electrolysis of water is

(A) Oxygen (B) Hydrogen (C) Chlorine (D) Nitrogen.

Ans. : (B) Hydrogen

15. Atomic number of chlorine is 17. The period number of this element in modern periodic table is

(A) 2 (B) 7 (C) 4 (D) 3.

Ans. : (D) 3

VIII. Answer the following questions : 4 × 1 = 4

16. State modern periodic law.

Ans. : “Properties of elements are periodic functions of their atomic numbers.”

17. Write any two uses of Plaster of Paris.

Ans. :

Plaster of Paris is used in :
Supporting fractured bones
Making toys Decorative materials
Making smooth surfaces. ( Any two )

18. Write the structural formula of ethene molecule.

Ans. :

19. ZnO + C → Zn + CO In this reaction name the reactant i) that is oxidised and ii) that is reduced.

Ans. :

Oxidised reactant is : C

Reduced reactant is : ZnO.

IX. Answer the following questions : 3 × 2 = 6

20. The pH values of A, B and C solutions are 5, 6 and 7 respectively. Which of these solutions is more acidic in nature ? Why ?

Ans. :

Solution A is more acidic.
As it has more + H ions.

21. Draw the diagram to show the arrangement of the apparatus used for testing the conductivity of salt solution and label ‘graphite rod’.

22. Give reason :

a) Metals are used in making cooking vessels.

b) Sodium metal is stored in kerosene.

Give reason :

a) When a calcium metal reacts with water, the liberated hydrogen gas does not catch fire.

b) Ionic compounds have high melting and boiling points.

Ans. :

a) Because, metals are good conductors of heat / having high melting points / property of malleability. ( Any one )

b) Sodium metal vigorously reacts with atmospheric oxygen and water, but not with kerosene.

a) The reaction of calcium with water is less violent. The heat evolved is not sufficient for the hydrogen to catch fire.

b) Because a considerable amount of energy is required to break the strong inter-ionic attraction.

X. Answer the following questions : 3 × 3 = 9

23. What is atomic size ? In the modern periodic table the atomic size decreases along a ‘period’ and increases down the ‘group’. Why ? Explain.

Ans. : The distance between the centre of the nucleus and the outermost shell of an isolated atom.

In modern periodic table atomic size decreases along the period because Electrons are being added to the outermost shell of an atom that tends to pull the electrons closer to the nucleus / No new shells are added to atom.

Atomic size increases down the group because New shells are being added, this increases the distance between the outer most electrons and the nucleus.

24. Draw the diagram of arrangement of the apparatus to show 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.

Ans. :

Reaction of zinc granules with dilute sulphuric acid :

25. Write the balanced chemical equation for the following chemical reactions :

i) Calcium carbonate → Heat Calcium oxide + Carbon dioxide

ii) Hydrogen + Chlorine → Hydrogen chloride

iii) Magnesium + Hydrochloric acid → Magnesium chloride + Hydrogen.

Which type of chemical reaction takes place when an iron nail is dipped in copper sulphate solution ? Why ? Write a balanced chemical equation for this chemical reaction.

Ans. :

i) CaCO3 → Heat -->CaO + CO 2

ii) H2 + Cl2 → 2HCl

iii) Mg + 2HCl → MgCl 2 + H 2

Chemical displacement reaction.
Because more reactive iron displaces copper from copper sulphate solution.
Fe + CuSO 4 → FeSO 4 + Cu.

XI. Answer the following question : 1 × 4 = 4

26. a) What are structural isomers ? Write the molecular and structural formula of butane.

b) What is catenation ? Write general formula for alkenes.

Ans. :

Carbon compounds having same molecular formula but different structural formulae
Molecular formula of butane is C4 H10

Structural formula of butane is

Carbon has unique ability to form bonds with other atoms of carbon, giving rise to large molecules.
General formula for alkene is Cn H 2n

PART - C ( BIOLOGY )

XII. Multiple choice : 2 × 1 = 2

27. Atmospheric layer that absorbs ultraviolet radiations coming from the sunlight is made up of this molecule.

(A) N2 (B) H2 (C) O3 (D) O2 .

Ans. : (C) O3

28. In humans, sexually transmitted viral infection is

(A) AIDS (B) Syphilis (C) Tuberculosis (D) Gonorrhoea.

Ans. : (A) AIDS

XIII. Answer the following questions : 2 × 1 = 2

29. What is the role of decomposers in an ecosystem ?

Ans. :

Decompose dead wastes ( organic ) of plants and animals thus keep surroundings clean and maintain ecological balance.

30. In males, testes are located outside the abdominal cavity in scrotum. Why ?

Ans. :

Because to maintain lower temperature required for the formation of sperms than the normal body temperature.

XIV. Answer the following questions : 3 × 2 = 6

31. Mention the function of the following plant hormones : i) Auxin ii) Cytokinin.

Ans. : i) Auxin : Helps the cells in the stems and the cells in the many parts of the plant body to grow longer. ( Any suitable answer )

ii) Cytokinin : Promotes cell division in fruits and seeds

Helps in promoting overall growth of plants. ( any one )

32. Draw the diagram showing the longitudinal section of a flower and label ‘ovary’.

Ans. :

33. Give reason : a) ‘Ventricles of the human heart have thick wall.’

b) ‘It is necessary to separate oxygenated and deoxygenated blood in mammals and birds.’

Ans. :

a) Since ventricles have to pump blood into various organs.

b) Since they need more energy to maintain their body temperature constant.

XV. Answer the following questions : 3 × 3 = 9

34. When a tall ( TT ) pea plant is crossed with a dwarf ( tt ) pea plant, represent the result obtained in 2 F generation of monohybrid cross with the help of checker board and mention the ratio of varieties of plants.

Ans. :

35. What is trophic level ? Flow of energy in an ecosystem is always unidirectional. Why ? Explain.

Ans. :

Different levels / stages of food chain.

Because,

The energy that is captured by autotrophs does not revert back to the solar input.
The energy which passes to the herbivores do not come back to autotrophs.
As energy moves progressively through the various trophic levels it is no longer available to the previous level.
At different levels energy is lost in the form of heat.

36. a) Mention any four main factors that lead to the rise of new species.

b) The experiences of an individual acquired during its lifetime cannot be passed on to its progeny. Give reason.

What are fossils ? Mention the methods of estimation of dating fossils and explain briefly.

Ans. :

a) Factors responsible for the rise of new species :

Geographical isolation
Natural selection
Inheritance of traits
Genetic drift / gene flow
Variation / mutuation / changes in DNA. ( Any four )

b) Change in non-reproductive tissues cannot be passed on to the DNA of germ cells.

Preserved traces of living organisms in deep layers of the earth.

Methods : i) Relative method : The fossils we find closer to the surface are more recent than fossils we find in deeper layers.

ii) Determining the time period by using isotopes ( dating ) Detecting the ratios of different isotopes of same element in the fossil material.

XVI. Answer the following questions : 2 × 4 = 8

37. Which molecule is formed during the first step of cellular respiration by the breakdown of glucose molecule in cytoplasm ? Mention the types of respiration and write any two differences between them.

Which are the factors essential for photosynthesis ? Mention the events that occur during this process and represent this process by balanced chemical resutilised:

Ans. :

Pyruvate.

Two types : i) Aerobic respiration ii) Anaerobic respiration

Aerobic respiration: Atmospheric oxygen is utilised. Liberates more energy with carbon dioxide and water. Takes place in micytoplasma. Takes place in higher levels of organisms

Anaerobic respiration: Atmospheric oxygen is not utilised. Liberates less energy with ethanol and carbon dioxide. Takes place in cytoplasm. Takes place in lower organisms like yeast.

Factors essential for photosynthesis : Carbon dioxide, water, minerals, sunlight and chlorophyll. Events that occur during photosynthesis :

i) Absorption of light energy by chlorophyll.

ii) Conversion of light energy into chemical energy.

iii) Splitting of water molecules into hydrogen and oxygen molecules.

iv) Reduction of carbon dioxide into carbohydrates.

Equation : 6CO2 + 12H2 → Sunlight--> C6 H12O6 + 6O2 + 6H 2O

38. Draw the diagram showing the structure of the human brain and label the following parts : i) Cerebrum ii) Cerebellum.