Bihar Board Class 10 · Science · Matric exam 2027
Bihar Board Class 10 Science Question Paper 2021
The board’s 2021 question paper, set G — all 110 questions as printed; 80 objective answers from the board’s own key; full model answers for 3 written questions, how the answer begins for 27 more. Each question names its chapter, where that chapter’s most-asked questions are.
Full marks 80 · Time 2 h 45 min
Section A · Objective questions (80)
1 mA is equal to
- (A) 10^-3 A ✓
- (B) 10^-2 A
- (C) 10^-1 A
- (D) 10^-6 A
Answer (the board’s key): (A)
Diesel is used in
- (A) Heavy vehicle
- (B) Rail engine
- (C) Electricity generation
- (D) All of these ✓
Answer (the board’s key): (D)
Solar cell converts solar energy into
- (A) Light energy
- (B) Kinetic energy
- (C) Thermal energy
- (D) Electrical energy ✓
Answer (the board’s key): (D)
The atomic number of Gold is
- (A) 29
- (B) 89
- (C) 79 ✓
- (D) 39
Answer (the board’s key): (C)
Which of the following is not a process of oxidation ?
- (A) Combustion
- (B) Respiration
- (C) Digestion of food
- (D) Precipitation ✓
Answer (the board’s key): (D)
The valancy of oxygen is
- (A) 1
- (B) 0
- (C) 2 ✓
- (D) 3
Answer (the board’s key): (C)
The pH value of acid rain should be
- (A) 5.6
- (B) less than 5.6 ✓
- (C) more than 5.6
- (D) 7.0
Answer (the board’s key): (B)
Which acid is found in ant-sting ?
- (A) Ethanoic acid
- (B) Citric acid
- (C) Methanoic acid ✓
- (D) Oxalic acid
Answer (the board’s key): (C)
Which of the following is conducting tissue ?
- (A) Epidermis
- (B) Phloem
- (C) Xylem
- (D) Both (B) and (C) ✓
Answer (the board’s key): (D)
By which process do protozoans excrete the excretory substance ?
- (A) Osmosis
- (B) Diffusion ✓
- (C) Absorption
- (D) Excretion
Answer (the board’s key): (B)
Largest gland of human body is
- (A) Pancreas
- (B) Ovary
- (C) Adrenal
- (D) Liver ✓
Answer (the board’s key): (D)
The body is balanced by the organ
- (A) Cerebellum ✓
- (B) Cranium
- (C) Brain stem
- (D) Cerebrum
Answer (the board’s key): (A)
Change in body in adolescence is due to
- (A) Testosterone
- (B) Estrogen
- (C) Thyroxine
- (D) both (A) and (B) ✓
Answer (the board’s key): (D)
How many chambers are there in human heart ?
- (A) Three
- (B) Four ✓
- (C) Eight
- (D) Two
Answer (the board’s key): (B)
What is blood ?
- (A) Tissue ✓
- (B) Cell
- (C) Matter
- (D) None of these
Answer (the board’s key): (A)
The word 'Gene' was coined by
- (A) Mendel
- (B) Darwin
- (C) Johannsen ✓
- (D) Lamarck
Answer (the board’s key): (C)
Rod of which of the following substances is used to make electromagnet ?
- (A) Steel
- (B) Brass
- (C) Soft iron ✓
- (D) None of these
Answer (the board’s key): (C)
The moving particle in a conducting wire carrying electric current is
- (A) atom
- (B) ion
- (C) proton
- (D) electron ✓
Answer (the board’s key): (D)
Ohm's law is
- (A) V = IR ✓
- (B) V = R^2I
- (C) V = I^2R
- (D) V = I + R
Answer (the board’s key): (A)
The S.I. unit of potential difference is
- (A) joule
- (B) watt
- (C) ampere
- (D) volt ✓
Answer (the board’s key): (D)
The resistance of Ammeter is
- (A) small
- (B) large
- (C) very small ✓
- (D) none of these
Answer (the board’s key): (C)
The filament of electric bulb is made of which metal ?
- (A) Copper
- (B) Nichrome
- (C) Lead
- (D) Tungsten ✓
Answer (the board’s key): (D)
The purpose of rheostat is
- (A) to increase the magnitude of current
- (B) to decrease the magnitude of current
- (C) both to increase or decrease the magnitude of current ✓
- (D) none of these
Answer (the board’s key): (C)
S.I. unit of electric charge is
- (A) volt
- (B) ohm
- (C) jule
- (D) coulomb ✓
Answer (the board’s key): (D)
Last product of respiration is
- (A) CO2 and H2O
- (B) CO2 and energy
- (C) H2O and energy
- (D) CO2, H2O and energy ✓
Answer (the board’s key): (D)
Uppermost layer of teeth is
- (A) Dentine
- (B) Enamel ✓
- (C) Bone
- (D) Crown
Answer (the board’s key): (B)
Longest part of human alimentary canal is
- (A) Stomach
- (B) Small intestine ✓
- (C) Oesophagus
- (D) Large intestine
Answer (the board’s key): (B)
Pollen grains are formed inside.
- (A) Anther ✓
- (B) Ovary
- (C) Style
- (D) Leaves
Answer (the board’s key): (A)
Sieve tube is found in.
- (A) Animals
- (B) Xylem
- (C) Phloem ✓
- (D) Unicellular plants
Answer (the board’s key): (C)
Lifespan of R.B.C. is
- (A) 120 days ✓
- (B) 180 days
- (C) 80 days
- (D) 220 days
Answer (the board’s key): (A)
Longest cell of human body is
- (A) Bone cell
- (B) Muscle cell
- (C) Neuron ✓
- (D) Master cell
Answer (the board’s key): (C)
Ovum is fertilized in
- (A) Vagina
- (B) Uterus
- (C) Ovary
- (D) Fallopian tube ✓
Answer (the board’s key): (D)
Which of the following is not a plant hormone ?
- (A) Ethylene
- (B) Cytokinin
- (C) Auxin
- (D) Oxytocin ✓
Answer (the board’s key): (D)
Male reproductive organ in plant flower is
- (A) Androecium ✓
- (B) Ovary
- (C) Stigma
- (D) Style
Answer (the board’s key): (A)
In which of the following binary fission does not occur ?
- (A) Amoeba
- (B) Yeast ✓
- (C) Paramoecium
- (D) Euglena
Answer (the board’s key): (B)
The source of energy in ecosystem is
- (A) Air
- (B) Sunlight ✓
- (C) Rainwater
- (D) Soil
Answer (the board’s key): (B)
Who among the following is known as 'Father of genetics' ?
- (A) Charles Darwin
- (B) Gregor Johann Mendel ✓
- (C) Lamarck
- (D) Weismann
Answer (the board’s key): (B)
Green plants are known as
- (A) Producer ✓
- (B) Consumer
- (C) Decomposer
- (D) none of these
Answer (the board’s key): (A)
Number of chromosomes in male gamete is
- (A) 22
- (B) 23 ✓
- (C) 24
- (D) 11
Answer (the board’s key): (B)
Ozone layer is found in
- (A) stratosphere ✓
- (B) exosphere
- (C) ionosphere
- (D) troposphere
Answer (the board’s key): (A)
Such elements which release electrons and form positive ions are known as
- (A) Metalloids
- (B) Metals ✓
- (C) Non-metals
- (D) Alloys
Answer (the board’s key): (B)
The process of coating of zinc on iron is known as
- (A) Electroplating
- (B) Corrosion
- (C) Galvanization ✓
- (D) Electrolysis
Answer (the board’s key): (C)
Which of the following is a covalent compound ?
- (A) NaCl
- (B) CaCl2
- (C) CH4 ✓
- (D) Na2O
Answer (the board’s key): (C)
Gold which is used to make ornaments is
- (A) 24 carat
- (B) 16 carat
- (C) 22 carat ✓
- (D) 15 carat
Answer (the board’s key): (C)
Which of the following is a noble element ?
- (A) Iodine
- (B) Silicon
- (C) Argon ✓
- (D) Bromine
Answer (the board’s key): (C)
An alloy of copper and tin is known as
- (A) Bronze ✓
- (B) Brass
- (C) Solder
- (D) Duralumin
Answer (the board’s key): (A)
The chemical formula of Plaster of Paris is
- (A) CaSO_4 . 5H_2O
- (B) CaSO_4 . 1/2 H_2O ✓
- (C) CaSO_4 . 2H_2O
- (D) CaSO_4 . H_2O
Answer (the board’s key): (B)
Acid reacts with base to form
- (A) strong base
- (B) strong acid
- (C) salt ✓
- (D) base
Answer (the board’s key): (C)
The slaked lime is
- (A) Ca(OH)_2 ✓
- (B) CaO
- (C) CaCO_3
- (D) Ca
Answer (the board’s key): (A)
Which of the following is not a base ?
- (A) CaO
- (B) NaCl ✓
- (C) NaOH
- (D) Na_2CO_3
Answer (the board’s key): (B)
An ore of zinc is
- (A) Cinnabar
- (B) Zinc blende ✓
- (C) Bauxite
- (D) Sodium chloride
Answer (the board’s key): (B)
Silicon is
- (A) Metal
- (B) Non-metal
- (C) Metalloid ✓
- (D) Alloy
Answer (the board’s key): (C)
Which of the following elements is not present in an alcohol ?
- (A) Carbon
- (B) Oxygen
- (C) Hydrogen
- (D) Nitrogen ✓
Answer (the board’s key): (D)
The common name of methanoic acid is
- (A) Formic acid ✓
- (B) Acetic acid
- (C) Tartaric acid
- (D) Lactic acid
Answer (the board’s key): (A)
Necessary for autotrophic nutrition is
- (A) Chlorophyll
- (B) Carbon dioxide and water
- (C) Sunlight
- (D) All of these ✓
Answer (the board’s key): (D)
Magnesium is found in
- (A) Chlorophyll ✓
- (B) R.B.C.
- (C) Chloroplast
- (D) W.B.C.
Answer (the board’s key): (A)
Oily paper is
- (A) Transparent
- (B) Opaque
- (C) Translucent ✓
- (D) None of these
Answer (the board’s key): (C)
What is the S.I. unit of magnification by lens ?
- (A) m
- (B) cm
- (C) mm
- (D) unitless ✓
Answer (the board’s key): (D)
Speed of light in different mediums is
- (A) equal
- (B) different ✓
- (C) both (A) and (B)
- (D) none of these
Answer (the board’s key): (B)
Speed of light in air in comparison to vacuum is
- (A) less
- (B) more
- (C) equal ✓
- (D) none of these
Answer (the board’s key): (C)
Number of principal foci in lens is
- (A) 1
- (B) 2 ✓
- (C) 3
- (D) 4
Answer (the board’s key): (B)
Good conductor of electricity is
- (A) Wood
- (B) Plastic
- (C) Carbon
- (D) Silver ✓
Answer (the board’s key): (D)
Negative electrode in dry cell is made of
- (A) Copper
- (B) Carbon ✓
- (C) Zinc
- (D) None of these
Answer (the board’s key): (B)
Value of 1 joule is
- (A) 0.24 calorie ✓
- (B) 4.18 calorie
- (C) 0.42 calorie
- (D) 2.4 calorie
Answer (the board’s key): (A)
In vegetable oils, there are
- (A) long saturated hydrocarbon chains
- (B) long unsaturated hydrocarbon chains ✓
- (C) small unsaturated hydrocarbon chains
- (D) small saturated hydrocarbon chains
Answer (the board’s key): (B)
How many isomers of butane are possible ?
- (A) 5
- (B) 2 ✓
- (C) 3
- (D) 4
Answer (the board’s key): (B)
What is the basis of the classification of the elements in Mendeleev's periodic law ?
- (A) Atomic radius
- (B) Atomic density
- (C) Atomic number
- (D) Atomic mass ✓
Answer (the board’s key): (D)
The ratio of numbers of atoms of nitrogen and hydrogen in ammonia molecule is
- (A) 3 : 1
- (B) 2 : 1
- (C) 1 : 2
- (D) 1 : 3 ✓
Answer (the board’s key): (D)
Which of the following is liquid at room temperature ?
- (A) Ethane
- (B) Ethyne
- (C) Ethanol ✓
- (D) Methane
Answer (the board’s key): (C)
Which of the following acids is found in vinegar ?
- (A) Sulphuric acid
- (B) Hydrochloric acid
- (C) Formic acid
- (D) Acetic acid ✓
Answer (the board’s key): (D)
Which of the following is an allotrope of carbon ?
- (A) Graphite
- (B) Diamond
- (C) Fullerene
- (D) All of these ✓
Answer (the board’s key): (D)
Compounds having same molecular formula but different structural formulae are known as
- (A) Isomers ✓
- (B) Allotropes
- (C) Catalysts
- (D) Polymers
Answer (the board’s key): (A)
Which mirror is used for shaving ?
- (A) Convex mirror
- (B) Plane mirror
- (C) Concave mirror ✓
- (D) None of these
Answer (the board’s key): (C)
The deviation of which colour of ray is the maximum in white light spectrum ?
- (A) Red
- (B) Green
- (C) Yellow
- (D) Violet ✓
Answer (the board’s key): (D)
Focal length of plane mirror is
- (A) infinity ✓
- (B) zero
- (C) 100 cm
- (D) 50 cm
Answer (the board’s key): (A)
A concave mirror gives real, inverted and same size image, if the object is placed
- (A) at pole
- (B) at infinity
- (C) at centre of curvature ✓
- (D) at focus
Answer (the board’s key): (C)
The twinkling of stars is due to
- (A) Atmospheric Reflection
- (B) Total Reflection
- (C) Atmospheric Refraction ✓
- (D) Total Refraction
Answer (the board’s key): (C)
The persistence of vision for human eye is
- (A) 1/10 sec
- (B) 1/16 sec ✓
- (C) 1/6 sec
- (D) 1/18 sec
Answer (the board’s key): (B)
Virtual image formed by convex mirror is
- (A) erect and magnified
- (B) inverted and magnified
- (C) erect and diminished ✓
- (D) none of these
Answer (the board’s key): (C)
The magnification ( m ) of concave lens is equal to
- (A) v/u ✓
- (B) uv
- (C) u/v
- (D) u + v
Answer (the board’s key): (A)
Section B · Written questions (30)
What should be the position of an object in front of convex lens for virtual and magnified image ? Draw a neat diagram.
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Model answer · image formation, convex lens
- 1.The object must be placed between the optical centre O and the principal focus F₁ of the convex lens.1 mark
- 2.Ray diagram: a ray from the top of the object parallel to the axis passes through F₂ after refraction, and a ray through O goes straight; the two diverge, and produced backwards they meet on the object's side, forming an enlarged, erect, virtual image.1 mark
Diagram: Draw a convex lens with principal axis, marking optical centre O, focus F1 and F2 on either side; place the object (an arrow) between O and F1 on the left; draw a ray parallel to the principal axis from the object top refracting through the lens to pass through F2, and a ray through the optical centre going straight; extend both refracted rays backward on the same side as the object to meet, forming a virtual, erect, enlarged image; label the image (a taller arrow) on the same side as the object.
Marks split from a structure derived from past papers (checked twice); not Bihar Board’s official scheme
Why does coin appear to be raised in water ?
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Model answer · refraction, coin in water
- 1.A coin placed in water appears to be raised above its actual position due to refraction of light. The light reaching our eye from the coin bends as it passes from water into air, so the coin seems displaced from its real position.1 mark
- 2.When light rays travel from a denser medium, water, to a rarer medium, air, they bend away from the normal. Due to this bending, the rays appear to come from a position higher than the actual position of the coin, forming a virtual image of the coin, which makes it look raised.1 mark
- Write the words 'refraction of light' in the first paragraph.
- State clearly that light bends away from the normal going from denser (water) to rarer (air) medium.
- Use the term 'virtual image' while explaining why the coin appears raised.
Marks split from a structure derived from past papers (checked twice); not Bihar Board’s official scheme
What is the defect of vision in human eye ? Name the types of vision defects.
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Model answer · defects of vision, human eye
- 1.When the human eye is unable to form a clear image of an object on the retina, it is called a vision defect. The vision becomes blurred due to the refractive defects of the eye, and the person cannot see the objects distinctly and comfortably.1 mark
- 2.There are mainly three types of vision defects in the human eye: myopia, hypermetropia, and presbyopia. Myopia is also known as near-sightedness, hypermetropia is also known as far-sightedness, and presbyopia arises due to the gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens.1 mark
- Write the exact words 'vision defect' and link it to the retina for point 1
- List all three names together: myopia, hypermetropia, and presbyopia for point 2
- Use the book's alternate names: near-sightedness and far-sightedness, to support the main terms
Marks split from a structure derived from past papers (checked twice); not Bihar Board’s official scheme
If the resistance of any electric bulb filament is 1200 ohm, how much electric current is required from source of 220 V ?
How the model answer begins
1. Given: resistance of the bulb filament R = 1200 Ω, potential difference V = 220 V. According to Ohm's law, R = V/I, so the formula for electric current is I = V/R. I = 220/1200
The full answer from Medha Ma’am →Write the 'Right hand thumb rule' regarding magnetic effect of current.
How the model answer begins
1. The right-hand thumb rule states that if we hold a current-carrying straight conductor in our right hand such that the thumb points towards the direction of current, then this gives the direction of current along the…
The full answer from Medha Ma’am →Write two drawbacks of alternating current.
How the model answer begins
1. Alternating current at high voltage is more dangerous — its shock is more severe; it also cannot be stored directly.
The full answer from Medha Ma’am →Define the intensity of electric current.
How the model answer begins
1. The intensity of electric current is defined as the amount of charge flowing through a cross-section of a conductor per unit time. If a net charge Q flows across any cross-section of a conductor in time t, then this…
The full answer from Medha Ma’am →Write three main properties of fuse wire.
How the model answer begins
1. The fuse wire has a very low melting point, so when an unduly high electric current flows through the circuit, the temperature of the fuse wire increases and it melts quickly, breaking the circuit.
The full answer from Medha Ma’am →The radius of curvature of a convex mirror which is used to see the back view in any automobile is 5 m. If a bus is at a distance of 5m, then find the position, nature and size of the image.
How the model answer begins
1. The radius of curvature of the convex mirror is R = +5 m, taking the positive sign because for a convex mirror the radius of curvature is behind the mirror. The focal length is given by f = R/2, so f = +5/2 = +2.5 m.
The full answer from Medha Ma’am →What is parallel combination of resistances ? Find the expression for equivalent resistance of parallel combination of resistances R1, R2 and R3.
How the model answer begins
1. When two or more resistors are connected such that the potential difference across each resistor is the same, it is called parallel combination. Three resistors R1, R2 and R3 are joined in parallel between two points X…
The full answer from Medha Ma’am →What happens when CO2 (gas) is passed through lime water, (i) in small amount (ii) in excess amount?
How the model answer begins
1. When carbon dioxide gas is passed through lime water in small amounts, the lime water turns milky. This happens due to the formation of calcium carbonate. The reaction is: Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)
The full answer from Medha Ma’am →What is a neutralization reaction ? Give one example.
How the model answer begins
1. The reaction in which an acid and a base react with each other to form salt and water is called a neutralisation reaction. It can be written in general as Base + Acid → Salt + Water.
The full answer from Medha Ma’am →What is meant by ductility?
How the model answer begins
1. The ability of metals to be drawn into thin wires is called ductility. This property of metals by which they can be drawn into thin wires is one of the important physical properties of metals.
The full answer from Medha Ma’am →Write the structural formula of ethyl alcohol.
How the model answer begins
1. The structural formula of ethyl alcohol (ethanol) is CH₃–CH₂–OH.
The full answer from Medha Ma’am →Write the structural formulae of butanone and ethanoic acid.
How the model answer begins
1. The structural formula of butanone is CH3-CH2-CO-CH3.
The full answer from Medha Ma’am →Why are iron objects galvanised?
How the model answer begins
1. Galvanisation of iron objects is done to protect them from rusting. In this process, a layer of zinc is coated on the surface of iron objects so that they do not come in direct contact with moisture and air.
The full answer from Medha Ma’am →What is baking powder?
How the model answer begins
1. Baking powder is a mixture of baking soda (sodium hydrogencarbonate, NaHCO3) and a mild edible acid such as tartaric acid.
The full answer from Medha Ma’am →What is a combination reaction?
How the model answer begins
1. A combination reaction is a chemical reaction in which two or more substances combine to form a single product.
The full answer from Medha Ma’am →Write the method of preparing methane gas in the laboratory and its chemical reaction with chlorine.
How the model answer begins
1. Methane gas is obtained in the laboratory by heating sodium acetate with soda lime. Sodium acetate (CH3COONa) is mixed with soda lime, which is a mixture of sodium hydroxide (NaOH) and calcium oxide (CaO), and the…
The full answer from Medha Ma’am →How is aluminium metal extracted from its ore?
How the model answer begins
1. The main ore of aluminium is bauxite (Al2O3.2H2O), which contains impurities like Fe2O3 and SiO2. This bauxite ore is concentrated by Bayer's process using NaOH solution to remove the impurities and obtain pure alumina…
The full answer from Medha Ma’am →What is bile? What is the significance of bile in human digestion?
How the model answer begins
1. Bile is a thick, green-yellow alkaline fluid secreted by the liver and stored in the gallbladder.
The full answer from Medha Ma’am →What is lymph? Explain its functions.
How the model answer begins
1. Lymph is a colorless fluid that filters out from blood plasma into the intercellular spaces present in between the cells of body tissues.
The full answer from Medha Ma’am →Write four main characteristics of living beings.
How the model answer begins
1. Living organisms undergo the process of nutrition to obtain energy. The food eaten gives the energy and raw material needed to maintain the body and to grow.
The full answer from Medha Ma’am →How many types of teeth are there in human? Write their names and functions.
How the model answer begins
1. There are four types of teeth in humans.
The full answer from Medha Ma’am →Write the differences between transpiration and translocation.
How the model answer begins
1. Transpiration is the process of loss of water in the form of vapour from the aerial parts of plants.
The full answer from Medha Ma’am →What is the significance of sexual reproduction?
How the model answer begins
1. Sexual reproduction leads to the generation of variations in the offspring. The DNA copying mechanism cannot be absolutely accurate, and the resultant errors are a source of variations in populations of organisms.
The full answer from Medha Ma’am →Write about contraceptive tablets.
How the model answer begins
1. Contraceptive pills act by changing the hormonal balance of the body so that eggs are not released, and fertilisation cannot occur. These drugs commonly need to be taken orally as pills. Since they change hormonal…
The full answer from Medha Ma’am →What is the role of acid in our stomach?
How the model answer begins
1. Hydrochloric acid present in the stomach kills the harmful bacteria present in the food that we eat, thus protecting the body from infection.
The full answer from Medha Ma’am →Describe the process of photosynthesis in plant with the help of labelled diagram.
How the model answer begins
1. Photosynthesis is the process by which autotrophs take in substances from the outside and convert them into stored forms of energy. Green plants make their own food in the form of carbohydrates by taking in carbon…
The full answer from Medha Ma’am →How does the transportation of oxygen and carbon dioxide take place in human being?
How the model answer begins
1. In human beings, the respiratory pigment is haemoglobin which has a very high affinity for oxygen, and this pigment is present in the red blood corpuscles. In the lungs, the passage divides into smaller and smaller…
The full answer from Medha Ma’am →
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