MG SCHOOL EDUCATION: KSEEB MQP 4 Key Answer

KSEEB - SCIENCE MQP - 4 2024-25

KEY ANSWER

PART A - PHYSICS

I. MCQ 3 × 1 = 3

1. The magnification of the image produced by a mirror is – 1·73. Then the nature of this image is

(A) Real and magnified (B) Real and diminished

Ans: (A) Real and magnified

2. A person clearly sees the objects placed at the distance of 40 cm to 80 cm only. This defect of the eye and a measure to rectify this defect are

(A) Myopia, use of suitable concave lens

(B) Hypermetropia, use of suitable convex lens

(D) Cataract, surgical treatment

Ans: (C) Presbyopia, use of suitable bifocal lens

3. A beam of white light is passed through two transparent media A and B. The colour of the scattered light from the medium A is blue and the colour of the scattered light from the medium B is white. The correct statement related to this phenomenon is

(A) size of the particles in medium A is more than that of B medium

(B) size of the particles in medium B is more than that of A medium

(D) densities of both A and B media are the same

Ans: (B) size of the particles in medium B is more than that of A medium

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

4. Draw the diagrams of circuit symbols of ‘wires crossing without joining’ and ‘rheostat’.

Ans:

5. “The absolute refractive index of a medium cannot be less than 1.” Justify this statement.

Ans: Because the speed of light in any medium is always less than that in a vacuum.

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

6. State the laws of reflection of light.

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

What is power of lens ? Write its SI unit.

Ans:

★ The power of a lens is defined as the reciprocal of its focal length

★ Diopter

7. Explain the method of preparing an electromagnet.

Ans:

★Wrap the insulated copper wire around the soft iron core,

★Connect the ends of the wire to the positive and negative terminals of the battery.

How can the strength of magnetic field generated by a circular coil of wire be increased? Explain.

Ans:

★ By increasing the number of turns of the coil.

★ By increasing the current flowing through solenoid.

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

8. What is magnetic field ? List any four properties of magnetic field lines.

Ans: Magnetic field is a region around a magnet where magnetic forces can be detected.

Properties of the magnetic field lines :

★ Emerge from north pole and merge at the south pole.

★ Closed curves

★ Never intersect each other

★ Have magnitude and direction.

What is short circuiting? Write any two measures that can be followed to prevent the possible damage due to short circuit.

Ans: When the live and neutral wires come into contact, which results in a large amount of current is called Short circuit

★ Wires should be well insulated.

★ Too many appliances should not be connected to a single socket.

9. An object is placed between F1 and 2F1 of convex lens. Draw the ray diagram to show the image formation. [ F1 : Principal focus of a lens ]

Ans:

10. Resistance of a metal wire of length 2m is 28Ω at 20°C. If the diameter of the wire is 0.04 mm then what will be the resistivity of the metal at that temperature?

Ans:

To find the resistivity of the metal, we can use the formula:

ρ = (R * A) / l

where:

ρ = resistivity

R = resistance = 28 Ω

A = cross-sectional area of the wire

l = length of the wire = 2 m

First, we need to find the cross-sectional area (A) of the wire:

A = π * (d/2)^2

where d is the diameter of the wire (0.04 mm = 0.00004 m):

A = π * (0.00004/2)^2 = 1.256 * 10^(-9) m^2

Now, we can calculate the resistivity:

ρ = (28 * 1.256 * 10^(-9)) / 2 = 1.76 * 10^(-8) Ωm

So, the resistivity of the metal at 20°C is approximately 1.76 × 10^(-8) Ωm.

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

11. Explain the following phenomena :

i) Formation of rainbow in the atmosphere

ii) Twinkling of stars.

Ans:

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

★Due to the dispersion of sunlight and internal reflection by the water droplets we see the rainbow colours.

ii)

★ The twinkling of stars is due to the atmospheric refraction of star light

★ Due to the changing in the position of the stars and the movement of the layers of the atmosphere. So the light from the stars is sometimes brighter and sometimes fainter and it appears to twinkle.

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

12. a) Connecting resistors in parallel in a circuit is better than connecting them in series. Why ? Explain.

b) State Joule’s law of heating. Explain how an electric bulb works on the basis of this law.

Ans:

★ Reduced Total Resistance

★ Increased Current Capacity

★ Same voltage across each resistor

★ Independent operation

The heat produced in a resistor is

i) directly proportional to the square of the current for a given resistance.

ii) directly proportional to the resistance for a given circuit.

iii) directly proportional to the time for which the current flows through the resistor.

★A strong metal with high melting point such as tungsten is used for making bulb filaments.

★ When electric current passes through a very thin, high resistance tungsten filament of an electric bulb, the filament becomes white-hot and emits light

PART – B ( CHEMISTRY )

VII. MCQ 3 × 1 = 3

13. The property of carbon atoms to form bonds with other carbon atoms to give large molecules is

(A) Isomerism (B) Allotropism

Ans: (C) Catenation

14. ZnO + C → Zn + CO ; the reactants that are oxidised and reduced in this chemical reaction respectively are

(A) ZnO and C (B) C and ZnO

Ans: (B) C and ZnO

15. When excess of sodium hydroxide is dissolved in the same basic solution then

(A) the concentration of OH − ions increases

(B) the concentration of H3O+ ions increases

(D) the concentration of OH − ions decreases.

Ans: (A) the concentration of OH − ions increases

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

16. Mention any two methods of preventing rancidity.

Ans:

★ Antioxidants are added to food.

★ Keeping food in airtight containers

17. Write the structural formula of the ketone having three carbon atoms.

Ans:

18. Aqueous solution of HNO3 shows acidic character but the solution of alcohol does not show this character. Why?

Ans: Because HNO3 readily releases hydrogen ions (H+) when dissolved in water, while alcohol does not release these ions.

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

19. Observe the following chemical reactions. Answer the question asked.

Name ‘a’ and ‘b’ products. Identify saturated and unsaturated product in ‘a’ and ‘b’.

Ans:

★ a - Ethene, b - fat / saturated carbon chain

★ a - unsaturated, b - saturated

20. Write the balanced chemical equation for the chemical reaction given below and identify the type of this reaction.

Lead nitrate + Potassium iodide → Lead iodide + Potassium nitrate.

Ans:

★ Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq)

★ Double displacement / precipitation reaction

21. Give reason for the following uses of baking soda :

i) As an ingredient in antacids

ii) As baking powder in bakeries.

Ans:

i) Because of its alkaline nature, which neutralizes stomach acid.

ii) Because it releases carbon dioxide, which makes baked goods rise.

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

22. Draw the diagram of arrangement of apparatus to show the action of steam on a metal and label the following parts : i) Metal sample ii) Hydrogen gas

23. a) While diluting an acid, water should not be added to the acid but acid should be added to water. Why? Explain.

b) Among one molar of hydrochloric acid and acetic acid, which of the acid is strong acid and which of the acid is weak acid? Give reason for your answer.

Ans:

a) Because adding water to an acid is highly exothermic, the large amount of heat generated, the mixture may splash out and cause burns.

★ Strong acid - hydrochloric acid, weak acid - acetic acid

★ Because hydrochloric acid completely ionizes in water, whereas acetic acid only partially ionizes.

One test tube has distilled water and other two test tubes have acidic and basic solutions. How can the nature of these three solutions be identified using red and blue litmus paper?

Ans:

★The solution that turns the red litmus paper blue is basic.

★The solution that turns the red litmus paper red is acidic;

★ The solution that doesn't change the color of the red and blu litmus paper is distilled water

24. Define the following : i) Structural isomers ii) Esterification iii) Micelles.

Ans:

i) Same molecular formula but different arrangements of atoms.

ii) Ethanoic acid reacts with absolute ethanol in the presence of an acid catalyst to give an ester.

ii) Micelles are the spherical structure in which The ionic-end of soap interacts with water while the carbon chain interacts with oil

a) What are substitution reactions ?

b) Name the simplest hydrocarbon and write its molecular formula.

c) What are oxidising agents?

Ans:

a) Substitution reaction is the one type of atom or a group of atoms takes the place of another /

Atom or a group of atoms in the compound are replaced by another atom.

b) Methane - CH4

c) An oxidizing agent is a substance that removes electrons from other substances,

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

25. a) Show the formation of magnesium chloride by the transfer of electrons.

b) Differentiate between calcination and roasting.

c) What are the constituent metals present in solder metal ? Why is solder metal used for welding electrical wires?

Ans:

CALCINATION	ROASTING
Process in which ore is heated in the absence of air.	This process is done in the presence of excess of air.
Calcination is used for carbonates and oxide ores.	Roasting is used for sulphide ores.

★ lead (Pb) and tin (Sn),

★ because of it has low melting point and easily melt.

PART – C ( BIOLOGY )

XII. MCQ 2 × 1 = 2

26. The second tropihc level of a food chain consists of

(A) Producers (B) Herbivores

Ans: (B) Herbivores

27. If a trait is appeared in the progenies of many generations, then the trait must be

(A) dominant trait (B) recessive trait

Ans: (A) dominant trait

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

28. ‘Stomata of leaves facilitate the transportation of water through xylem.’ Justify.

Ans: Stomata facilitate the transpiration which creating a suction force that pulls water up from the roots through the xylem.

29. ‘Vegetative propagation can be considered as a boon to the farmers.’ How?

Ans: By adopting vegetative propagation, farmers can increase crop yields, reduce costs, and improve the overall efficiency of their farming operations.

30. Father alone is responsible to determine the sex of a child. Why?

Ans: father's contribution of either an X or a Y chromosome determines the sex of the child.

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

31. Mention the needs for the separation of non-biodegradable wastes in the waste management.

Ans:

★ To prevent pollution

★ To recycling and reuse

★ To save landfill space

★ To reduce health risk

32. Draw the diagram to show the germination of pollen on stigma and label ‘pollen tube’.

Ans:

33. Name the process that takes place in the part labelled as B in the structure given below. What is the significance of this process?

(This Question not clear)

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

34. Draw the diagram to show the structure of the human brain and label the following parts : i) Cerebellum ii) Pons.

Ans:

35. Round, yellow seeds ( RRYY ) producing pea plant is crossed with wrinkled, green seeds ( rryy) producing pea plant. Write the checker board to show the results obtained in the F2 generation of this cross. What is the phenotypic ratio of the plants produced in F2 generation?

Ans:

Phenotypic ratio - 9:3:3:1

Tall pea plant ( TT ) is crossed with dwarf pea plant ( tt ). What kind of plants will be produced in F1 generation? Draw a checker board to show the results obtained in F2 generation when pea plants of F1 generation are self pollinated. What is the phenotypic ratio of the plants produced here?

Ans:

36. a) ‘Reflex arcs are considered as more efficient for quick responses.’ Justify.

b) When a plant receives light from one direction then the plant appears to bend towards the direction of light. Analyse the reason for this response.

Ans:

a) Because involve fewer neurons, a shorter pathway, no brain processing, and faster signal transmission.

★ Plants bend towards light because of a plant hormone called auxin.

★ Auxin is produced at the shoot tip and moves to the shady side of the plant.

★ This causes the cells on the shady side to grow longer,

★ which makes the plant appear to bend towards the light.

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

37. a) Mention the types of blood vessels in the human body and write one function of each.

b) What is double circulation?

Ans:

★ Arteries: it carry oxygenated blood away from the heart to various organs of the body.

★ Capillaries: Exchange of material between the blood and surrounding takes place across the thin wall of smallest vessels, the capillaries. The capillaries then join together to form veins.

★ Veins: it carry the deoxygenated blood away from the organ or tissue.

b) Blood passes through the heart twice in one cycle.

38. a) What is the role of testes and prostate gland in human male reproductive system?

b) How does an embryo get nutrition from the mother’s blood? Explain.

Ans:

★Testes: it produce sperm cells and the male sex hormone testosterone,

★ Prostate gland: it secret fluid which helps nourish and allowing them to move

★ With the help of a special disc shaped tissue called placenta.

★ It contains villi on the embryo’s side and blood spaces on the mother’s side.

★This provides glucose and oxygen to the developing embryo.

★ Removes the wastes generated from the embryo.

a) What are the different methods of contraception followed in human beings?

b) Mention one difference between fragmentation and regeneration.

Ans:

★Barrier method : condom, diaphragm and cervical caps.

★ Chemical method : oral and vaginal pills

★ Intrauterine contraceptive devices : copper-T

★ Surgical method : vasectomy in males and tubectomy in females

Fragmentation	Regeneration
The organism breaks-up into smaller pieces upon maturation, each piece develops into new individual	If organism is somehow cut or broken into many pieces, each piece grows into a complete organism
Ex: Spirogyra	Ex: Planaria

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