MG SCHOOL EDUCATION: KREIS - Science Model Question Paper

Key Answer

MGSS

KREIS - SSLC SCIENCE MODEL QUESTION PAPER – 2

Sub: Science Sub. Code: 83E Time: 3.15 Hour Max Marks: 80

PART A: PHYSICS

I. Four alternatives are given for each of the following questions. Choose the correct alternative and write the complete answer along with its letter of alphabet. 3×1=3

1. Instrument used to detect electric current is _______

A) Galvanometer B) Fuse C) Ammeter D) Voltmeter

Ans: A) Galvanometer

2. At the time of short circuit, the current in the circuit

A) Reduce substantially B) Does not change

C) Increases heavily D) Vary continuously

Ans: C) Increases heavily

3. Which one of the following material cannot be used to make a lens?

A) Water B) Glass C) Plastic D) Clay

Ans: D) Clay

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

4. What is Lens formula?

Ans:

The relation between distance of object, distance of image and focal length for a lens is called lens formula

u – Image distance, v – Object distance, f – Focal length

5. What is the S.I. Unit of Potential difference? Name the device used to measure the potential difference.

Ans:

· The SI unit of potential difference is volt.

· A voltmeter is an instrument that is used to measure the potential difference across a conductor

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

6. On what factors do the resistant of a conductor depends?

Ans:

· The type of material.

· The length of the conductor.

· The thickness of the conductor.

· The temperature of the conductor.

7. State Snell’s law of refraction with formula.

Ans:

Snell’s law State that “The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, for the light of a given colour and for the given pair of media”.

Sin i/sin r = constant

8. How much work is done in moving a charge of 2C across two points having potential difference 12Volt?

Ans:

q = 2C

V = 12V

W = V × q

W = 12V × 2C

W= 24 J.

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

9. Draw the Ray diagram, when object is placed in between F1 and 2F1 of a convex lens. And write nature, position and size of the image.

Ans:

Position of the image beyond 2f2

Nature real, inverted and enlorged

Describe the size and nature of the image formed by the convex lens when object placed in the following positions, i. At infinity ii. At 2F1 iii. Between principle focus F and optical centre O.

Ans:

i. At infinity

· Size of the image is highly diminished

· Nature of the image is Real and Inverted

ii. At 2F1

· Size of the image is same size

· Nature of the image is Real and Inverted

iii. Between principle focus F₁ and optical centre O.

· Size of the image is enlarged

· Nature of the image is virtual and erect

10. Draw diagram of simple electric motor.

Ans:

11. In a school there are 70 teachers. Most of them come by their personnel vehicle, where as there are many teachers who come from the same place. In this practice of coming will help nature? Justify it.

Ans:

· Most of them come by their personnel vehicle, they are promoting negligence towards environment, careless spending of resources but others are promoting environmental concern, sharing, helpfulness.

· many teachers who come from the same place, this way of commuting is nature friendly because they are saving fossil fuels, which are non-renewable sources of energy, by this practice and also reducing pollution.

· By switching off the lights and fans when not in use, turning off the engine of vehicles at red lights.

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

12. Draw the circuit diagram for, Resistance in parallel and write advantages of parallel combination over series combination.

Ans:

· In parallel combination each appliance gets the full voltage.

· If one appliance is switched on/of others are not affected.

· The parallel circuit divide the current through the appliances. Each appliance gets proper current depending on its resistance.

· In a parallel combination it is very easy to connect or disconnect a new appliance without affecting the working of other appliances.

13. What is magnetic field? Mention the characteristics of magnetic field lines.

Ans:

The area around a magnet where a magnetic force is experienced is called the magnetic field.

Magnetic field lines emerge from the north pole and merge at the south pole.
As the distance between the poles increases, the density of magnetic lines decreases.
The direction of field lines inside the magnet is from the South Pole to the North Pole.
Magnetic lines do not intersect with each other.

PART B: CHEMISTRY

VI. Four alternatives are given for each of the following questions. Choose the correct alternative and write the complete answer along with its letter of alphabet. 3×1=3

14. The name of Carbon compound

A) Methanal B) Methanone C) Ethanoic acid D) Ethanal.

Ans: C) Ethanoic acid

15. Sulphide ore Reduction Purification. The process that has to be done in the empty space is,

A) Electrolysis B) Calcination C) Roasting D) Oxidation.

Ans: B) Calcination

16. The Non metal with electrical conductivity is,

A) Iodine B) Diamond C) Sulphur D) Graphite

Ans: D) Graphite

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

17. State Modern Periodic law.

Ans:

Modern Periodic Law which states that: Physical and chemical properties of the elements are the periodic function of their atomic numbers.

18. The metallic property of elements increase down the group in the modern periodic table. Why?

Ans: Metallic character increases down a group due to increase in atomic size. Thus, the outermost electrons are farther away from the nucleus and therefore can be lost easily. Hence, the electropositive character or metallic character increases

19. Write four methods to prevent corrosion.

Ans:

· By painting.

· BY applying grease or oil.

· By galvanisation:The process of depositing a thin layer of zinc metal on iron.

· By tin plating and chromium plating.

· By alloying it.

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

20. Why is metal oxide called a basic oxide? Name the products obtained when copper oxide reacts with dilute Hydrochloric acid.

Ans:

Metallic oxides are basic in nature because they react with dilute acids to form salt and water. Copper(II) oxide dissolves in mineral acids such as hydrochloric acid, sulfuric acid or nitric acid to give the corresponding copper(II) salts.

CuO + 2 HCl → CuCl2 + H2O.

Test tube A contains distilled water, test tube B contains acidic solutions and test tube C contains basic solution. How these samples could be identified using red litmus paper?

Ans:

· The solution which turns red litmus paper to blue contains a basic solution.

· Divide the obtained blue litmus paper into two parts.

· The solution from the test tube which turns blue litmus paper to red will be the acidic solution.

· Solution of the test tube which do not change either red or blue litmus paper contain water.

21. Draw a neat diagram showing Electrolytic refining of Copper and label the following parts: i. Cathode ii. Anode mud.

Ans:

22. Write Molecular and Molecular and structural formula for i. Benzene. ii. Butanol.

Ans:

Molecular formula of Benzene is C₆H₆Molecular formula of Butanol is C₄H₉OH

Structural formula of Benzene is Structural formula of Butanol is

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

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

Ans:

24. Write the differences between saturated carbon compounds and unsaturated carbon compounds. Carbon forms covalent bonds with other atoms but not ionic bonds. Why?

Ans:

Saturated hydrocarbons

Saturated hydrocarbons containing only single covalent bonds. These are also known as alkanes.
These compounds are less reactive.
Saturated hydrocarbons burns with blue flame

Unsaturated hydrocarbons

Unsaturated hydrocarbons are the straight chain compounds containing double or triple covalent bonds are known as alkenes and alkynes.
These compounds are more reactive.
Unsaturated hydrocarbons burns with sooty flame.

Explain the mechanism of cleaning action of Soap.

Ans:

Soaps and detergents contain two parts. A long hydrocarbon part which is hydrophobic (water repelling) in nature and a short ionic part which is hydrophillic (water attracting) in nature.
The hydrocarbon part of the soap molecule links itself to the oily (dirt) drop and ionic end orients itself towards water and forms a spherical structure called micelles. The soap micelles helps in dissolving the dirt in water and wash our clothes.

25. Give reasons for the following;

i. Ionic compounds in solid state do not conduct electricity where as molten state are good conductor of electricity.

ii. Silver articles when exposed to air gradually it turn blakish.

iii. Chemical reactions does not takes place when copper is added to iron sulphate solution.

Ans:

I. i. in a solid state, the ions cannot move and thus there is no flow of charge but in molten state, the anions and cations are free to move therefore it conduct electricity.

II. ii. Silver article when exposed to air gradually turn blackish because silver metal react with sulphur present in atmosphere and forms a layer of silver sulphide which is of black in colour.

iii. Copper less reactive than iron. It is placed at the bottom of the reactivity series, below iron. Therefore, copper cannot displace iron from iron sulphate solution.

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

26. Explain the properties of Carbon compounds.

Ans:

Chemical Properties of Carbon Compounds: The important chemical properties are as follows:

Combustion: Carbon burns in air or oxygen to give carbon dioxide and heat and light.
C(s) + O₂(g) → CO₂(g) + Heat and light

Oxidation reaction: Carbon and its compounds get easily oxidized when subjected to combustion. For example alcohol on oxidationis converted to carboxylic acid.

Addition Reaction: Addition of dihydrogen with unsaturated hydrocarbon in the presence of catalysts such as nickel or platinum or palladium are known as Hydrogenation (addition) reaction.

Substitution Reaction: Replacement of one or more hydrogen atom of an organic molecule by another atom or group of the atom is known as Substitution Reaction.

PART C: BIOLOGY

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

27. the part of neuron that receive information is,

A) Axon B) Synapse C) Dendrites D) Cell body.

Ans: C) Dendrites

28. Cause for Ozone depletion is,

A) Chlorofluoro carbon B) Oxygen C) Hydrogen D) Nitrogen.

Ans: A) Chlorofluoro carbon

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

29. What are Nephrons?

Ans:

Nephron is the structural and functional unit of Kidney.

30. Who determines the sex in a child?

Ans:

A child's gender (male or female) is determined by the chromosome that the male parent contributes.

31. Mention the hormone responsible for diabetes.

Ans:

the hormone responsible for diabetes is insulin

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

32. Mention disadvantages of constructions of Dams.

Ans:

Environmental problem - deforestation leading to loss of biodiversity
building a dam is very expensive
Social problem - nearby towns and villages becomes homeless, Displacement of people during construction.
There are chances of flooding, have to be relocated. They lose their businesses and farms

33. Write the differences between arteries and veins.

Ans:

Arteries

· Involved in carrying oxygenated blood except for pulmonary arteries.

· Valves are absent

veins.

· Involved in carrying deoxygenated blood except for pulmonary veins

· Valves are present

What is double circulation?

Ans:

In the human heart, blood passes through the heart twice in one cardiac cycle. This type of circulation is called double circulation. One complete heartbeat in which all the chambers of the heart contract and relax once is called cardiac cycle. Double circulation ensures complete segregation of oxygenated and deoxygenated blood which is necessary for optimum energy production in warm-blooded animals.

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

34. Explain the significant function of each structure in human male reproductive system.

Ans:

Scrotum. The bag of skin that holds and helps to protect the testicles.
The testicles make sperm and, the temperature of the testicles needs to be cooler than the inside of the body.
The prostate gland is to produce the fluid that nourishes and transports sperm (seminal fluid).
The vas deferens transports mature sperm to the urethra in preparation for ejaculation.
The urethra thus forms a common passage for both the sperms and urine.

Explain the structure and important role of placenta during pregnancy period of women.

Ans:

The placenta is defined a disc shaped organ that develops during pregnancy in mammals.
It attaches the fetus to the uterus of the mother during pregnancy.
The placenta provides oxygen and nutrients to the growing fetus in the uterus of the mother.
The waste materials from the fetus are excreted through the placenta.

35. Draw the diagram showing the structure of Nephrons and label the following parts; i. Bowman’s capsules. ii. Collecting duct.

Ans:

36. What is monohybrid cross? With help of checker board, write the monohybrid ratio of F2 generation between tall and dwarf pea plants.

Ans:

Monohybrid cross is a cross between parents differing in only one trait or in which only one trait is being considered.

Phenotypic ratio = 3: 1 (3 tall and 1 dwarf)

What are homologous and analogous organs? Give examples for both.

Ans:

Analogous organs : Those organs which have different basic structure (or different basic design) but have similar appearance and perform similar functions are called analogous organs.

For example, The wings of an insect and a bird are analogous organs.

Homologous organs : Those organs which have the same basic structure (or same basic design) but different functions are called homologous organs.

For example, the wing of a bat, flipper of a seal, front leg of a horse and arm of a man are homologous organs.

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

37. Draw a neat diagram of Human brain and label the following parts

i. Pons. ii. Cerebrum.

Ans:

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

38. a) Name the mineral required for production of thyroxin hormone.

What is the use of this hormone to our body?

What happens when the deficiency of this hormone occurs?

b) What are involuntary actions? Name the parts of human brain that control voluntary and involuntary actions?

Ans:

The mineral element required for the synthesis of thyroid hormones is iodine.
Thyroid hormones play vital roles in regulating the body's metabolic rate, controlling heart, muscle and digestive function, brain development and bone maintenance.
Deficiency is the leading cause for Goiter.

Involuntary action is the set of muscle movement which do not require thinking. But it is controlled by brain for example beating of heart beat.
The medulla controls the involuntary actions whereas forebrain is responsible for controlling the voluntary actions in the body.