Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev

Science Class 10

Class 10 : Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev

The document Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev is a part of the Class 10 Course Science Class 10.
All you need of Class 10 at this link: Class 10

Class-X
Science Theory
TIME: 3 Hrs.
M.M: 80
General Instructions:

Read the following instructions very carefully and strictly follow them :
1. The question paper comprises four sections A, B, C and D. There are 36 questions in the question paper. All questions are compulsory.
2. Section - A - question no. 1 to 20 - all questions and parts thereof are of one mark each. These questions contain multiple choice questions (MCQs), very short answer  questions and assertion - reason type questions. Answers to these should be given in one word or one sentence.
3. Section - B - question no. 21 to 26 are short answer type questions, carrying 2 marks each. Answers to these questions should in the range of 30 to 50 words.
4. Section - C - question no. 27 to 33 are short answer type questions, carrying 3 marks each. Answers to these questions should in the range of 50 to 80 words.
5. Section - D - question no. - 34 to 36 are long answer type questions carrying 5 marks each. Answer to these questions should be in the range of 80 to 120 words.
6. There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.
7. Wherever necessary, neat and properly labeled diagrams should be drawn.

SECTION A

Q.1. Give reason why do chips manufacturers usually flush bags of chips with gas such as nitrogen ?    (1 Mark)
Ans: To prevent the oil and fats of the chips from being oxidized or become rancid.

Q.2. On which factor does the colour of the scattered white light depend ?    (1 Mark)
Ans: Size of the particles of the medium through which it is passing.

Q.3. What is a homologous series of carbon compounds ?    (1 Mark)
Ans: A homologous series is the family of organic compound having the same functional group, and the successive (adjacent) members of which differ by CH2 unit or 14 mass unit.

Q.4. State two physical properties of gold which are of extreme use to jewellers.    (1 Mark)
Ans: Malleability, ductility, lustrous.

Q.5. What is the role of acid in our stomach ?    (1 Mark)
Ans: HCl of gastric juice disinfects the food and acidifies it for proper functioning of proteolytic enzyme pepsin.

Q.6. What is fertilisation ? Where does it occur in a human female ?    (1 Mark)
Ans: Fusion of male and female gamete is known as fertilization. It occurs in fallopian tube.
OR 
What is micturition ?
Ans: It is the expulsion of urine from the body.

Q.7. List two biotic components of an ecosystem.    (1 Mark)
Ans: Plants, animals, micro-organisms.
OR
What is food chain ?
Ans: Food chain is a simple representation of energy flow in nature. It represents the series of organisms which eat other organisms any may in turn be eaten themselves.

Q.8. Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved ?    (1 Mark) 
(i) It turns lime water milky
(ii) It extinguishes a burning splinter
(iii) It dissolves in a solution of sodium hydroxide
(iv) It has a pungent odour
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (ii), (iii) and (iv)
(d) (i) and (iv)
Ans: (b) Sodium hydrogen carbonate when reacts with acetic acid evolves carbon dioxide gas. Carbon dioxide gas turns lime water milky, extinguishes fire on a burning splinter and dissolves in a solution of sodium hydroxide.
OR
Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same ?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
(a) (i) and
(ii) (b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)

Ans: Metals are good conductors of heat and have high melting points. Thus, Aluminium is used for making utensils.

Q.9. A student determines the focal length of a device ‘X’ by focusing the image of a distant object on a screen placed 20 cm from the device on the same side as the object. The device ‘X’ is    (1 Mark)
(a) Concave lens of focal length 10 cm
(b) Convex lens of focal length 20 cm
(c) Concave mirror of focal length 10 cm
(d) Concave mirror of focal length 20 cm
Ans: (d) Image formed by the concave mirror in this case is same as when object is at infinity. Due to the great  distance, light rays will incident almost parallel to principal axis. After reflection all the rays will converge and meet at a principal focus. So, focal length is 20 cm.
OR
Which of the following can make a parallel beam of light when light from a point source is incident on it?

(a) Concave mirror as well as convex lens
(b) Convex mirror as well as concave lens
(c) Two plane mirrors placed at 90° to each other
(d) Concave mirror as well as concave lens
Ans: (a) When a point source of light is placed at the focus of concave mirror then all light rays after reflection through mirror will become parallel to the principal axis. When this point source of light is placed at the focus of convex lens then after falling on convex lens it will become parallel to the principal axis.

Q.10. A spherical mirror and a thin spherical lens have each a focal length of – 15 cm. The mirror and the lens are likely to be    (1 Mark)
(a) both concave
(b) both convex
(c) the mirror is concave and the lens is convex
(d) the mirror is convex, but the lens is concave
Ans: (a) As per the sign convention, the focal length of a concave mirror and a concave lens are taken as negative. Hence, both the spherical mirror and the thin spherical lens are concave in nature.

Q.11. At noon the sun appears white as    (1 Mark)
(a) light is least scattered
(b) all the colours of the white light are scattered away
(c) blue colour is scattered the most
(d) red colour is scattered the most
Ans: (a) Sun is directly over the head and sunlight travel relatively shorter distance causing only little of the blue and violet colours to be scattered.

Q.12. What will happen if deer is missing in the food chain given below ?    (1 Mark)
Grass → Deer → Tiger
(a) The population of tiger increases.
(b) The population of grass decreases.
(c) Tiger will start eating grass.
(d) The population of tiger decreases and the population of grass increases.
Ans: (d) Explanation : If deer is missing in the food chain then :
(i) There will be no herbivore to consume grass, hence population of grass will increase.
(ii) Tiger will start dying of hunger, therefore, the population of tiger will decrease.
OR
Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the _____________ (a) food web (b) ecological pyramid (c) ecosystem (d) food chain
Ans: (a) Food web
Explanation : Food web is a network of food chains. Each organism is generally eaten by two or more kinds of organisms which are again eaten by several other organisms and so instead of straight line food chain, the series of organisms dependent on one another for their food can be shown by branched chain which is called as a food web.

Q.13. Select the mismatched pair in the following and correct it.    (1 Mark)
(a) Bio-magnification — Accumulation of chemicals at the successive trophic levels of a food chain
(b) Ecosystem — Biotic components of environment
(c) Aquarium — A man-made ecosystem
(d) Parasites — Organisms which obtain food from other living organisms
Ans: (b) Ecosystem- Biotic components of environment
Explanation : Both biotic and abiotic components of environment constitute an ecosystem.

Q.14. Directions : For question number 14 , two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below :    (1 Mark)
(a) Both A and R are true and R is correct explanation of the assertion.
(b) Both A and R are true but R is not the correct explanation of the assertion.
(c) A is true but R is false.
(d) A is false but R is true.
Assertion (A) : The resistivity of conductor increases with the increasing of temperature.
Reason (R) : The resistivity is the reciprocal of the conductivity.
Ans: (b) The resistivity of the conductors is directly proportional to temperature.

Q.15. Directions : For question numbers 15, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below :    (1 Mark)
(a) Both A and R are true and R is correct explanation of the assertion.
(b) Both A and R are true but R is not the correct explanation of the assertion.
(c) A is true but R is false.
(d) A is false but R is true.
Assertion (A) : Two bar magnets attract when they are brought near to each other with the same pole.
Reason (R) : Unlike poles will attract each other.
Ans: (d) Two bar magnets repel when same poles face each other. This is called repulsion. Opposite poles attract each other, but similar poles repel.

Q.16. Directions : For question numbers 16, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below :    (1 Mark)
(a) Both A and R are true and R is correct explanation of the assertion.
(b) Both A and R are true but R is not the correct explanation of the assertion.
(c) A is true but R is false.
(d) A is false but R is true.
Assertion (A) : Plasmodium reproduces by multiple fission.
Reason (R) : Multiple fission is a type of asexual reproduction.
Ans: (b) Both A and R are true but R is not the correct explanation of the assertion.

Q. Directions : Q. No 17 - 20 contain five sub-parts each. You are expected to answer any four subparts in these questions.
Q.17. Study the given experimental set-up and answer any four questions.
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
(a) The above experimental set up shows reaction between metal and    (1 Mark)
(i) Acid
(ii) Metal carbonate
(iii) Metal hydrogen carbonate
(iv) Metal oxide
Ans: (a) (i) It is a reaction between a metal (Zn) and an acid (H2SO4)

(b) Which gas is liberated during the process?    (1 Mark)
(i) Hydrogen gas
(ii) Carbon dioxide gas
(iii) Nitrogen gas
(iv) Hydrogen sulphide gas

Ans: (i) During the reaction between a metal and an acid, hydrogen gas is released.

(c) Identify the balanced chemical equation for the given reaction.    (1 Mark)
(i) Zn + H2SO4 → ZnSO4 + H2
(ii) 2Zn  +  2H2SO4 → 2ZnSO4 + 2H2
(iii) Zn + 2H2SO4 → 2ZnSO4 + H2
(iv) 2Zn  + H2SO4 → 2ZnSO4 + H2
Ans: (i) Zn + H2SO4 → ZnSO4 + H

(d) What will happen if NaOH is used in place of dil. sulphuric acid and the test tube is heated?    (1 Mark)
(i) It will produce sodium zincate (salt) and hydrogen gas.
(ii) It will produce sodium sulphate and hydrogen gas.
(iii) It will produce sodium zincate (salt) and carbon dioxide gas.
(iv) It will produce sodium sulphate and carbon di oxide gas. 
Ans: (i) It will produce sodium zincate (Salt) and hydrogen gas. Zn (s) + 2NaOH (aq) → Na2ZnO2 (aq)  + H2 (g)

(e) How will you test for the gas evolved ?    (1 Mark)
(i) Bring a glowing splint near test tube, it will reignite.
(ii) Bring moist litmus paper is placed in a test tube of this gas, it turns red. 
(iii) Bring a burning splint near the opening of a test tube containing this gas, a popping sound occurs.
(iv) Using universal litmus solution.
Ans: (iii) Test for H2 gas : The presence of H2 gas can be tested by passing the gas through soap solution and then bringing a burning splinter near the soap bubbles filled with the gas. If the gas burns with a pop sound, it is hydrogen.

Q.18. The given diagram represents female reproductive system. Study the diagram and answer any four questions.

Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev

(a) Which part produces ovum?    (1 Mark)
(i) 4
(ii) 5

(iii) 6
(iv) 7
Ans: (iv) The label 7 represents ovary. Ovum is produced by ovaries.

(b) The process of fertilisation takes place in which of the following part?    (1 Mark)
(i) 4
(ii) 5
(iii) 6
(iv) 7
Ans: (ii) The label 5 represent oviduct / fallopian tube. It is the site of fertilisation.

(c) Where does the implantation of embryo takes place ?    (1 Mark)
(i) Part 1
(ii) Part 2
(iii) Part 3
(iv) Part 4
Ans: (iv) Implantation of embryo takes place in part 4, which represents uterus.

(d) In which part, block is created surgically to prevent fertilisation ?    (1 Mark)
(i) Part 4
(ii) Part 5
(iii) Part 6
(iv) Part 7
Ans: (ii) In part 5, which represents oviduct, block is created surgically to prevent fertilization.

(e) Which of the following events is likely to take place, if the nuclei from an 8-celled stage of an embryo are transplanted into enucleated eggs?    (1 Mark)
(i) Recipient egg dies
(ii) Donor nuclei die in the new environment
(iii) Cleavage occurs but is arrested after some time
(iv) Formation of the viable embryo in the recipient eggs

Ans: (iv) The zygote divides repeatedly to form a mass of cells known as embryo. This embryo gets attached to the inner layer of the uterine cavity, i.e., endometrium. It thickens every month and is supplied with blood to nourish the embryo. Soon it gets covered by rapidly dividing uterine cells. This leads to pregnancy.

Q.19. Read the following and answer any four questions.
A student fixes a sheet of white paper on a drawing board. He places a bar magnet in the centre of it. He sprinkles some iron filings uniformly around the bar magnet. Then he taps the board gently and observes that the iron filings arrange themselves in a particular pattern.
(a) Why do the iron filings arrange in a pattern?    (1 Mark)
(i) Due to force exerted by the magnet within its magnetic field.
(ii) Due to force exerted by the magnet outside the magnetic field.
(iii) Due to pressure of magnetic field.
(iv) Due to gravitational force.

Ans: (i) Due to the force exerted by the magnet within its magnetic field.

(b) The lines along which the iron filings align represent ___________. It moves from _________ .    (1 Mark)
(i) Gravitational force, North to South pole
(ii) Magnetic field lines, South to North pole
(iii) Gravitational force, South to North pole
(iv) Magnetic field lines, North to South pole

Ans: (iv) The lines represent magnetic field lines.

(c) What does the crowding of iron filings at the end of the magnet indicate?    (1 Mark)
(i) Magnetic field is weaker near the poles of the magnet.
(ii) Magnetic field is strongest near the poles of the magnet.
(iii) Magnetic field is neither weaker nor strongest near the poles of the magnet. 
(iv) None of these
Ans: (ii) Crowding of iron filings at the ends of the magnet indicates that the magnetic field is strongest near the poles of the magnet.

(d) Which of the following statements is correct about magnetic field strength?    (1 Mark)
(i) Closer the lines, more will be the strength and farther the lines, lesser will be the field strength.
(ii) Closer the lines, less will be the strength and farther the lines, more will be the field strength.
(iii) Magnetic field strength is same everywhere.
(iv) None of these
Ans: (i) The strength of magnetic field is indicated by the closeness of the field lines. Closer the lines, more will be the strength and farther the lines, lesser will be the field strength. 

(e) Which of these is not a source of magnetic field?    (1 Mark)
(i) Magnet
(ii) Moving charges
(iii) Electric current
(iv) Battery
Ans: (iv) Battery is not a source of magnetic field while other magnet, moving charges, and electric current are sources of magnetic field.

20. Read the following and answer any four questions.
In a thermite reaction, a compound of iron reacts with a metal.
(a) Which of the following metal is used in this reaction?    (1 Mark)
(i) Copper (Cu)
(ii) Aluminium (Al)
(iii) Magnesium (Mg)
(iv) Zinc (Zn)
Ans: (ii) Aluminium (Al)

(b) After completion of this reaction, a metal is obtained in the molten state. Identify the metal.    (1 Mark)
(i) Zinc (ii) Copper
(iii) Aluminium
(iv) Iron
Ans: (iv) Iron (Fe)

(c) The correct reaction in the form of a balanced chemical equation is:    (1 Mark)
(i) Fe2O3 + 2Al → 2Fe + Al2O3 + Heat.
(ii) Fe2O3 + Al → Fe + Al2O3 + Heat.
(iii) 2Fe2O3 + 2Al → 2Fe + 2Al2O3 + Heat.
(iv) 2Fe2O3 + Al → 2Fe + Al2O3 + Heat.
Ans: (i) Fe2O3 + 2Al → 2Fe + Al2O3 + Heat.

(d) Mention the most common use of this reaction is:    (1 Mark)
(i) In paints and varnishes
(ii) In making of gold jewellery
(iii) To join railway tracks or cracked machine parts
(iv) In heating element of electric geysers.
Ans: (iii) To join railway tracks or cracked machine parts.

(e) The reaction of metal with Al is ___________.    (1 Mark)
(i) Endothermic
(ii) Exothermic
(iii) Redox reaction
(iv) None of these
Ans: (ii) The reaction of metal with aluminium is exothermic.

SECTION B

Q.21. 1 g of copper powder was taken in a China dish and heated. What change takes place on heating? When hydrogen is passed over this heated substance, a visible change is seen in it. Give the chemical equations of reactions.    (2 Mark)
Ans: The black colour substance formed by the reaction of copper with oxygen is Copper (II) oxide (CuO).
Chemical Reaction: 2Cu + O2 - 2CuO Hydrogen gas is passed over this heated material (CuO), the black coating on the surface turns brown as the reverse reaction takes place and copper is obtained.
CuO+ H2 → Cu+ H2O

Q.22. State Mendeleev ’s periodic law. Write two achievements of Mendeleev ’s periodic table.    (2 Mark)
Ans: Mendeleev’s Periodic Law : “Properties of elements are the periodic function of their atomic masses.” Achievements :
(i) It could classify all the elements discovered at that time.
(ii) It helped in discovery of new elements.
(iii) It helped in correction of atomic mass of some of the elements.
OR
State the modern periodic law for classification of elements. How many (a) groups and (b) periods are there in the modern periodic table ?
Ans: “Properties of elements are the periodic function of their atomic number.”
(i) There are 18 groups.
(ii) There are 7 periods in the modern periodic table.

Q.23. Name one nitrogenous waste present in urine. What is the basic filtration unit of kidney called?    (2 Mark)
Ans: Nitrogenous waste present in urine is uric acid or urea. The basic filtration unit of kidney is nephron.

Q.24. (a) Why did Mendel choose garden pea for his experiments ? Write two reasons.    (2 Mark)
(b) List two contrasting visible characters of garden pea Mendel used for his experiment.

Ans: (a) Reasons :
(i) Pea plant is small and easy to grow.
(ii) A large number of true breeding varieties of pea plant are available.
(iii) Short life cycle.
(iv) Both self and cross-pollination can be made possible.
(b) Contrasting characters :
Round / Wrinkled seeds
Tall / Short plants
White / Purple flowers
Green / Yellow seeds

Q.25. What are magnetic field lines ? How is the direction of magnetic field at a point in a magnetic field determined using field lines ?    (2 Mark)
Ans: (a) Magnetic field line
Path along which a hypothetical free north pole would tend to move. By drawing a tangent to the magnetic field line at that point.
OR
(b) Yes.
With change in current in the coil X, the magnetic field associated with it also changes around the coil Y placed near it. This change in magnetic field induces a current in the coil Y.

Q.26. “The number of trophic levels in a food chain is limited.” Give reason to justify this statement.    (2 Mark)
Ans: In a food chain, the number of trophic levels are limited to 4-5. This is because according to 10% law of energy transfer, only 10% of energy passes from one trophic level to next. Thus the amount of energy goes on decreasing with successive trophic levels. After five trophic levels, existence of organisms would become impossible with such negligible amount of energy.
OR
We do not clean natural ponds or lakes but an aquarium needs to be cleaned regularly. Why is it so ?

Ans: We need to clean of aquarium because of the :
(i) absence of natural decomposer.
(ii) stagnancy of water.

SECTION C

Q.27. Identify the acid and the base from which sodium chloride is obtained. Which type of salt is it ? When is it called rock salt ? How is rock salt formed ?    (3 Mark)
Ans: Acid – Hydrochloric acid/HCl
Base – Sodium hydroxide/NaOH
Neutral Salt
When it forms brown crystals combined with impurities.
Drying up of seas.

OR
(a) For the preparation of cakes, baking powder is used. If at home your mother uses baking soda instead of baking powder, how will it affect the taste of the cake and why ?
(b) How is baking soda be converted into baking powder ?
(c) What makes the cake soft and spongy ?
Ans:
(a) The cake will have a bitter taste because of the formation of Na2CO3/sodium carbonate while baking/heating.
(b) By adding tartaric acid
(c) The liberated CO2 gas.

Q.28. Write the names given to the vertical columns and horizontal rows in the Modern Periodic Table. How does the metallic character of elements vary on moving down a vertical column ? How does the size of atomic radius vary on moving left to right in a horizontal row ? Give reason in support of your answer in the above two cases.    (3 Mark)
Ans: Vertical Column — Groups
Horizontal Rows — Periods

(i) Metallic character increases.
Reason : Ability to lose electrons increases on moving down the group due to increase in distance between the nucleus and the valence electrons/decrease in the attraction between the nucleus and the valence electrons.

(ii) Atomic radius decreases.
Reason : The nuclear charge increases on moving from left to right across a period resulting in increase in the attraction between the nucleus and the valence electrons.

Q.29. (i) Define Genetics.
(ii) Who is regarded as the ‘Father of Genetics’ ? Name the plant on which he performed his experiment.
(iii) Why did he select that specific plant for his experiments ?    (3 Mark)
Ans: (i) Genetics is the branch of biology that deals with the study of heredity and variations.
(ii) Gregor Johann Mendel, garden pea.
(iii) Garden pea plants were easily available / they grow in one season / fertilization was easy.

Q.30. Write the functions of the following parts of human female reproductive system : (i) Ovary, (ii) Fallopian tube, (iii) Uterus.    (3 Mark)
Ans: (i) Ovary : Produces egg or female gamete, female sex hormone / estrogen.
(ii) Fallopian tube : Transfer of ovum to the uterus, site for fertilization
(iii) Uterus : Site of implantation of zygote, development of embryo.

Q.31. State the cause of dispersion of white light passing through a glass prism. How did Newton show that white light of sun contains seven colours using two identical glass prisms. Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the focus of the first prism.    (3 Mark)
Ans: Cause of dispersion of white light : 
Different colours of light bend through different angles with respect to the incident ray as they pass through a prism.

Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
OR
Define angle of deviation. Why do different components of white light split up into spectrum when it passes through a triangular glass prism ? Show the angle of deviation for red colour when white light passes through a prism.
Ans: The angle between the extended incident ray and the emergent ray is called the angle of deviation. This is because the different colours travel through a glass prism at different speeds.

Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
Q.32. The resistance of a wire of 0.01 cm radius is 10 Ω. If the resistivity of the material of the wire is 50 × 10–8W.m, find the length of the wire.    (3 Mark)
Ans: Given, Radius, r = 0.01 cm = 0.01 × 10–2 m.
Resistivity, r =  50 × 10–8 Wm.
Resistivity, R = 10 W
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
Length = Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev

Q.33. What is solenoid ? Draw the field lines of the magnetic field produced on passing current through and around a current carrying solenoid.    (3 Mark)
Ans: Definition : A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called solenoid.
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
Magnetic field lines through and around a current carrying solenoid.

Q.34. (a) List in tabular form any three chemical properties on the basis of which metals and nonmetals are differentiated.
(b) State two ways to prevent the rusting of iron.    (5 Mark)
Ans: (a)

Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
(b) (i) Painting
(ii) Oiling
(iii) Galvanization
(vi) Alloying

Q.35. Mention the organ and site of photosynthesis in green plants. What are the raw materials essential for this process ?  How are they obtained ? Write complete balanced chemical equation for the process. Name the by-products.    (5 Mark)
Ans: Photosynthesis takes place in the grana and stroma of the chloroplast (Plastid) in green parts of plants. The raw materials required for this process are carbon dioxide and water in the presence of sunlight and chlorophyll. Carbon dioxide enters the leaves through stomata and cells of the roots absorb water from the soil. Balanced equation for photosynthesis :
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev 
The by-products in this process is the evolution of oxygen gas.
OR
(i) Draw the diagram of cross section of a leaf and label the following parts :
(a) chloroplast
(b) cuticle
(ii) A gas is released during photosynthesis. Name the gas and also state the way in which the gas is evolved.
(iii) In certain group of plants, stomata remain closed during day. How is food synthesized by such plants ? Also name them.

Ans:
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
(ii) Oxygen
By splitting of water (photolysis)
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
(iii) They take up CO2 at night through stomata, which open during night and produce an intermediate organic acid which is acted upon by the energy absorbed by chlorophyll during the day and breaks up to release of CO2. The CO2 so produced internally is used in photosynthesis during day when stomata are closed.
Desert plants. [Xerophytic CAM plants]

Q.36. An object is placed at a distance of 30 cm from a concave lens of focal length 30 cm.
(i) Use lens formula to determine the distance of the image from the lens.
(ii) List four characteristics of the image (nature, position, size, erect/inverted) in this case.
(iii) Draw a labelled diagram to justify your answer of part (ii).    (5 Mark)

Ans: (i) u = – 30 cm, f = –30 cm, v = ?
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
∴ v = – 15 cm
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
Distance of the image will be 20 cm in front of lens.
(ii) Nature : Virtual
Position : 15 cm from lens on the same side as the object
Size : Diminished
Erect/Inverted : Erect
(iii)
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
OR
(i) A lens produces a magnification of – 0.5. Is this a converging or diverging lens ? If the focal length of the lens is 6 cm, draw a ray diagram showing the image formation in this case.
(ii) A girl was playing with a thin beam of light from a laser torch by directing it from different directions on a convex lens held vertically. She was surprised to see that in a particular direction, the beam of light continues to move along the same direction after passing through the lens. State the reason for her observation. Draw a ray diagram to support your answer.

Ans: (i) The image will be real and inverted, since the magnification has negative value. The lens that can produce a real and inverted image is a converging/ convex lens.
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev
In the figure OF1 = OF2 = 6 cm.
(Marks will be deducted if arrows are not shown)
(ii) The girl must have directed the ray of light along the direction of the optical centre of the lens because the ray of light passes straight through the optical centre of the lens.
Sample Question Paper (2020-21) - 4 Class 10 Notes | EduRev

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