MG SCHOOL EDUCATION: Science State Level preparatory Key Answer

STATE LEVEL SSLC PREPARATORY EXAM-2025

KEY ANSWER

PART - A ( PHYSICS )

I. MCQ 3×1=3

1. In a young adult having normal vision the distance of far point of the eye is

(A) 25 cm

(B) infinite distance

(D) 50 cm

Ans: (B) infinite distance

2. One property of magnetic field lines among the following is

(A) inside the magnet, the direction of magnetic field lines is from its south pole to north pole

(B) magnetic field lines intersect each other

(D) magnetic field lines are not closed curves

Ans: (A) inside the magnet, the direction of magnetic field lines is from its south pole to north pole

3. The nature of the image formed by a concave lens is

(A) virtual and inverted

(B) virtual and erect

(D) real and inverted

Ans: (B) virtual and erect

II. Answer the following questions: 3×1=3

4. "The sky appears black in colour to the person at space station." Justify.

Ans: There is no atmosphere in space and hence light does not scatter.

5. Observe the figure given below. The same type of metal wires X and Y are connected to the ammeters P and Q respectively. Which of these ammeters indicates more flow of current and why ?

Ans:

★ P

★ Because resistance is inversely proportional to the cross sectional area of the conductor

6. A ray of light travelling in crown glass enters obliquely into the air. Does the light ray bend towards the normal or away from the normal? Why?

Ans:

★ Bends away from the normal.

★ Because light travels faster in air than in glass.

III. Answer the following questions: 2×2=4

7. Draw a diagram to show the pattern of concentric circles indicating the field lines of a magnetic field around a straight conducting wire.

Ans:

8. Draw a ray diagram to show the image formation when the object is kept at 'C' of a concave mirror. [C = Centre of curvature ]

Ans:

IV. Answer the following questions: 3x3=9

9. a) State the laws of reflection of light.

b) What is the 'aperture' of a spherical lens ?

a) State the laws of refraction of light.

b) What is the 'power of a lens'?

Ans:

i) The angle of incidence is equal to the angle of reflection

ii) The incident ray, the normal to the mirror at the point of incidence and the reflected ray all lie in the same plane.

b) Aperture of a lens is the diameter of its light transmitting area.

i) 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.

ii) The ratio of sine of angle of incidence to the sine of angle of refraction is a constant for the light of a given colour and for the given pair of media

(OR) sini/sinr = Constant.

b) The power of a lens is the reciprocal of its focal length in meters.

10. a) Observe the direction of electric current and the direction of the motion of the rod AB in the given diagram. Name the magnetic pole represented by the end X of the magnet.

State the rule that helps to determine the direction of magnetic pole.

b) What are the reasons for overloading that occur in an electric circuit?

Ans:

★ X - North pole

★ Stretch left hand's thumb, forefinger, and middle finger so they are perpendicular to each other. forefinger in the direction of the magnetic field, Middle finger in the direction of the current and thumb in the direction of the force.

★ when the live wire and the neutral wire come into direct contact

★ Accidental hike in the supply voltage.

★ Connecting too many appliances to a single socket.

(Any Two)

11. a) "In domestic electric circuit, connecting electric devices in parallel is suitable instead of connecting them in series." Justify.

b) "Only alloys are used in the coils of wires of electric iron box and electric toasters." Justify.

Ans:

★ 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.

★ Because they have a higher melting point and resistivity.

V. Answer the following questions: 2x4=8

12. a) What is near sightedness (myopia)? What are the causes for this defert?

b) Explain the phenomenon of the formation of rainbow in the atmosphere

Ans:

★ It is a defect of the eye in which far objects appear blurry but near objects are clear.

Causes

i) Excessive curvature of the eye lens.

ii) Elongation of the eyeball.

★ Rainbow is a natural spectrum appearing in the sky after a rain shower

★ It is caused by dispersion of sunlight by tiny water droplets, present in the atmosphere.

★The water droplets act like small prisms

★ Due to the dispersion of light and internal reflection, different colours reach the observer’s eye.

13. A washing machine connected to a 220 V generator draws a current of 10 A. Then what is the power of that washing machine? If it is used for 6 hours in a day then calculate the total cost of the energy to operate it for 30 days at Rs. 5 per 1 kWh?

Ans:

Given

V= 220

I = 10A

P =?

P = V × I

P = 220 × 10

P = 2,200W

----------

t = 6 × 30 = 180hrs

P = 2200W = 2.2KW

E = P × t

E = 2.2 × 180

E = 396kwhr

Cost = 396 × 5 = 1980rs

a) The resistance of the filament of an electric bulb is 880 Ω and the resistance of the coil of an electric heater is 1100 Ω. Both are connected to an electric source of potential difference 220 V. Then

i) find the current drawn by each instrument

ii) which instrument draws more current ?

b) How much work is done in moving a charge of 5 C across two points having a potential difference of 25 V?

Ans:

Given:

Electric bulb resistance R = 880Ω

Electric heater resistance R = 1100Ω

V = 220V

Current drawn by Electric bulb:

I = V/R

I = 220/880

I = 0.25A

Current drawn by Electric heater:

I = V/R

I = 220/1100

I = 0.2A

Electric bulb draws more current.

Given

W =?

Q = 5 C

V = 25 V

W = V × Q

W = 25 × 5

W = 125 j

𝗣𝗮𝗿𝘁 - 𝗕 ( 𝗖𝗵𝗲𝗺𝗶𝘀𝘁𝗿𝘆 )

VI. MCQ 3x1=3

14. 2AgCl → 2Ag+ Cl; the type of this chemical reaction is

(A) Combination reaction

(B) Displacement reaction

(D) Double displacement reaction

Ans: (C) Decomposition reaction

15. The total number of covalent bonds present in nitrogen molecule is

(A) 4 (C) 2 (B) 1 (D) 3

Ans: (D) 3

16. FeSO4 + X→ Fe + XSO4; In this chemical equation 'X' represents

(A) P (B) Cu (C) Hg (D) Zn

Ans: (D) Zn

VII. Answer the following questions: 3x1=3

17. Name the sodium compound that is used for softening of hard water.

Ans: Sodium Carbonate

18. Which ions produce a white precipitate when the solution of sodium sulphate is added to the solution of barium chloride?

Ans: Ba^2+ and SO4^2-

19. How is the concentration of hydroxide ions (OH) affected when excess base is dissolved in a solution of potassium hydroxide ?

Ans: Concentration of hydroxide ions (OH⁻) increase.

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

20. Define the following with respect to the carbon compounds:

i) Structural isomers

ii) Hydrogenation.

What are functional groups? Name the functional groups present in propanal and propanol.

Ans:

i) Same molecular formula but different structures is called structural isomers.

ii) The addition of hydrogen to an unsaturated hydrocarbon to get a saturated hydrocarbon.

★ Group of atoms that give specific properties to carbon compounds.

★ Propanal : aldehyde / -CHO

★ Propanol : alcohol / -OH

21. Write any four properties of ionic compounds.

Write any four physical properties of metals.

Ans:

★They're hard and brittle.

★They have high melting points and high boiling points

★They are soluble in water but insoluble in organic solvents.

★They conduct electricity when dissolved in water or when melted.

★ Sonorous

★ Lustrous

★ Ductile

★ Malleable

★ Hard and brittle

★ Conduct heat and electricity

(Any four)

22. Which solution will be formed after the electrolysis of brine solution? How do you determine the nature of that solution by using red and blue litmus papers ?

Ans:

★ Sodium hydroxide / NaOH / Basic

★ Red litmus paper will turn blue, indicating a basic (alkaline) solution.

IX. Answer the following questions: 3x3=9

23. a) Balance the following chemical equations:

i) NaOH + H₂SO₄ → Na₂SO₄ + H₂о

ii) K + O2 →K2O

b) ZnO + C → Zn+CO; write the reactants that are oxidised and reduced in this reaction.

Ans:

i) 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂о

ii) 4K + O2 →2K2O

★ Oxidised reactant: C

★ Reduced reactant : ZnO

a) List the changes that take place during chemical reactions.

b) Write the balanced chemical equation for the following reaction:

Calcium hydroxide + Carbon dioxide →Calcium carbonate + Water

Ans:

★ Change in state

★ Change in colour

★ Evolution of a gas

★ Change in temperature

Ca(OH)2 + CO2 →CaCO3 + H2O

24. Draw the diagram of the arrangement of apparatus used to show the action of steam on a metal and label the following parts:

i) Glass wool soaked in water

ii) Delivery tube

Ans:

25. Give reasons for the following:

i) Plaster of Paris is stored in dry place

ii) Solution of glucose does not exhibit acidic properties

iii) Milk mixed with baking soda takes longer time to set as curd.

Ans:

i) Because Plaster of Paris absorbs moisture to form a hard solid known as gypsum.

ii) Glucose do not dissociate in water to form hydrogen ions.

iii) Because baking soda neutralizes the acids that form when milk turns to curd

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

26. a) Write the structural formula of the following carbon compounds:

i) Benzene

ii) Ethyne

b) Explain the mechanism of cleaning action of soaps

Ans:

ii)

★ The molecules of soap are sodium or potassium salts of long chain carboxylic acids.

★ The ionic end of soap interacts with water while the carbon chain interacts with oil.

★ The soap molecules thus form structure called micelles. This forms an emulsion in water.

★ The soap micelles thus helps in pulling out the dirt in water and we can wash our clothes clean.

𝗣𝗮𝗿𝘁 - 𝗖 ( 𝗕𝗶𝗼𝗹𝗼𝗴𝘆 )

XI. MCQ. 2×1=2

27. A non-biodegradable substance that leads to biomagnification is

(A) Plastic (C) Glass (B) DDT (D) Teflon

Ans: (B) DDT

28. Brown coloured young mice are produced in F, generation by black coloured male rat and brown coloured female rat. Then the genotype of F, progeny is

(A) Bb (C) B (B) b (D) BB

Ans: (A) Bb

XII. Answer the following questions: 2×1=3

29. Name any two viral infections that transmit through unprotected sexual contact.

Ans: AIDS and Warts

30. The role of 'synapse' is significant in the continuous transmission of nerve impulses. How?

Ans:

★ Converting electrical signals into chemical signals

★ Allowing for the continuous flow of electrical signals throughout the nervous system.

XIII. Answer the following questions: 3x2=6

31. Draw the diagram showing the structure of nephron.

Ans:

32. a) What are trophic levels ?

b) Construct a grassland food chain with three trophic levels.

Ans:

a) Trophic levels are the different steps in a food chain.

b) Grass →Grass Hopper →Frog →Snake

33. What is double circulation? Mention two advantages of this process.

Ans:

★ Blood passes through the heart twice in one cycle.

Advantages:

★ Prevent mixing of oxygenated and deoxygenated blood.

★ Suply sufficient oxygen to maintain constant body temperature.

XIV. Answer the following questions. 3×3=9

34. Draw a diagram showing the structure of human brain and label the following parts:

i) Cerebrum

ii) Cerebellum.

Ans:

35. Mention the major events that occur during photosynthesis process. In what form the food produced in this process get store in the plants?

a) Name the product produced by the breakdown of glucose molecule in the cytoplasm.

b) Name the type of respiration that takes place in mitochondria and yeast cells. Mention the products produced during these processes.

Ans:

i) Chlorophyll absorbs light energy.

ii) The light energy is converted into chemical energy when the water molecules are split into hydrogen and oxygen.

iii) Carbon dioxide is reduced to carbohydrates.

★ Starch

★ Pyruvate

Mitochondria :

★ Aerobic respiration

★ Producing carbon dioxide and water

Yeast cell :

★ Anaerobic respiration

★ Produces ethanol and carbon dioxide

36. Name the hormones secreted by the glands given below. Write their functions:

i) Thyroid gland

ii) Adrenal gland

iii) Pancreas

a) Give an example for each of the following tropic movements found in the plants:

i) Geotropism

ii) Hydrotropism

iii) Phototropism

iv) Chemotropism

b) Name the part of central nervous system that controls the reflex action.

Ans:

i) Thyroxin : Controls carbohydrate, protein and fat metabolism

ii) Adrenaline: Prepares the body to deal with emergency situations.

iii) Insulin: Regulates blood sugar levels.

i) Roots grow downwards towards the earth.

ii) Roots grow towards the source of water.

iii) Shoots grow towards light.

iv) Pollen tubes grow towards the ovules.

b) Spinal cord

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

37.

a) Yellow seeds (YY) producing pea plant is crossed with green seeds (yy) producing pea plant. Show the results of the plants produced in F2, generation with the help of a checker board. Write the phenotypic and genotypic ratio of the plants produced.

b) In humans, the sex of the child is determined by father. How? Justify.

Ans:

★ The father determines the sex of the child by contributing either an X or a Y chromosome.

★ If he contributes an X chromosome, the offspring will be female (XX).

★ If he contributes a Y chromosome, the offspring will be male (XY).

XVI. Answer the following question: 1x5=5

38. a) What are the various contraceptive methods followed in humans?

b) Write any one difference between fragmentation and regeneration.

c) What changes occur in a flower after the fertilization?

Ans:

★ Barrier methods: Condoms, Diaphragm

★ Chemical methods: Oral pills, Vaginal pills

★ Physical method: Copper T

★ Surgical method : Vasectomy and Tubectomy

Fragmentation	Regeneration.
breaks up into smaller pieces upon maturation and these pieces grow into new individuals. Ex: Spirogyra	can be cut into any number of pieces and each piece grows into a complete organism. Ex: Planaria