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VIII SCIENCE TERM-1 ALL LESSON BOOK BACK ONE MARK QUESTION ANSWERS
TERM - I
MEASUREMENT
One Mark Questions
I.CHOOSE THE BEST ANSWER:
1. Which one of the following systems of units is the British system of units? FPS
2. Electric current belongs to base quantities.
3. SI unit of temperature is Kelvin.
4. Luminous intensity is the intensity of visible light.
5. Closeness of two or more measured values is called as precision.
6. Which one of the following statements is wrong?
Approximation gives accurate value.
II. FILL IN THE BLANKS:
1. The solid angle is measured in steradian.
2. The coldness or hotness of a substance is expressed by temperature.
3. Ammeter is used to measure electric current.
4. One mole of a substance, contains 6.023 X 10 23 atoms or molecules.
5. The uncertainty in measurement is called as Error.
6. The closeness of the measured value to the original value is Accuracy.
7. The intersection of two straight lines gives us plane angle.
III.TRUE OR FALSE:
1. Temperature is a measure of total kinetic energy of the particles in a system. FALSE
2. If one coulomb of charge is flowing in one minute it is called ampere. FALSE
3. Amount of substance gives the number of particles in the substance. TRUE
4. Intensity of light coming from a candle is approximately equal to one ‘candela’.
TRUE
5. Quartz clocks are used in GPS devices. FALSE
6. Angle formed at the top of a cone is an example of ‘plane angle’. TRUE
7. The number 4.582 Can be rounded off as 4.58. TRUE
IV.MATCH THE FOLLOWING:
1. Temperature - measure of hotness or coldness
2. Plane angle - angle formed by the intersection of two planes
3. Solid angle - Angle formed by the intersection of three or more planes.
4. Accuracy - closeness to the actual value
5. Precision - closeness to two or more measurements
V.ASSERTION & REASON:
1. Assertion : The SI system of units is the suitable system for measurements.
Reason: The SI unit of temperature is Kelvin.
Answer (b) both assertion and reason are true but reason is not the correct explanation of the assertion.
Correct explanation:
In SI system the units are precisely defined and have the same value everywhere.
2. Assertion : Electric current, amount of substance, luminous intensity are the fundamental physical quantities.
Reason: They are independent of each other.
Answer (b) both assertion and reason are true and reason is the correct explanation of the assertion.
3. Assertion : radian is unit of solid angle
Reason: one radian is the angle subtended at the centre of a circle by an arc of length equal to its radius
Answer: Assertion is false, but reason is true.
Correct explanation : Radian is the unit of plane angle.
VI. ANSWER VERY BRIEFLY:-
1. How many base quantities are included in SI system?
Seven
2. Give the name of the instrument used for the measurement of temperature?
Thermometer
3. What is the SI unit of ‘Luminous intensity’?
Candela
4. What type of oscillations are used in atomic clocks?
Periodic Vibration
5. Mention the type of clocks based on their display?
Analog clock, Digital clock
6. How many times will the ‘minute hand’ rotate in one hour?
One time
7. How many hours are there in a minute?
60 minutes = 1hour
FORCE AND PRESSURE
One Mark Questions
I. Choose the best answer:
1. If we apply force against the direction of motion of the body, then the body will stop moving.
2. Pressure exerted by a liquid is increased by the density of the liquid and the height of the liquid column
3. Unit of pressure is Pascal and Nm–2
4. The value of the atmospheric pressure at sea level is 76 cm of mercury column
5. Pascal’s law is used in hydraulic lift, brake system and pressing heavy bundles
6. Which of the following liquids has more viscosity? Grease
7. The unit of viscosity is poise
II. Fill in the blanks.
1. The pressure of a liquid column increases with the depth of the column.
2. Hydraulic lift works under the principle of Pascal’s law
3. The property of surface tension of a liquid surface enables the water
droplets to move upward in plants.
4. A simple barometer was first constructed by Torricelli
III. True or false:
1. Force acting on a given area is called pressure. True
2. A moving body comes to rest due to friction alone. True
3. A body will sink if the weight of the body is greater than the buoyant force. True
4. One atmosphere is equivalent to 1,00,000 newton force acting on one square metre. True
5. Rolling friction is slightly lesser than the sliding friction.False
6. Friction is the only reason for the loss of energy. True
7. Liquid pressure decreases with the decrease of depth. True
8. Viscosity depends on the pressure of a liquid. True
IV. Match the following:
A.
1. Static friction - Objects are at rest
2. Kinetic friction - Objects are in motion
3. Rolling friction - Least friction
4. Friction between the liquid layers - Viscosity
5. Sliding friction - Objects are sliding
B.
1. Barometer - Atmospheric pressure
2. Increasing friction - Increasing area of contact
3. Decreasing friction - decreasing area of contact
4. Lubricants - reduce friction
5. Irregular surface - cause of friction
V. Complete the analogy.
1. Knot in a thread : static friction :: Ball bearing : rolling friction
2. Downward force : Weight :: Upward force offered by liquid : Buoyant force
VII. Consider the statements given below and choose the correct option.
1. Assertion : Sharp knives are used to cut the vegetables.
Reason : Sharp edges exert more pressure.
Answer: (a) Both assertion and reason are true and the reason is the correct explanation of the assertion
2. Assertion : Broad straps are used in bags.
Reason : Broad straps last for long life.
Answer: (b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion
Correct explanation: The weight of the bags falls on a larger area of the shoulder. So lesser pressure is produced.
3. Assertion : Water strider slides easily on the surface of water.
Reason : Water striders experience less buoyant force.
Answer: (b) If both assertion and reason are true, but reason is not the correct explanation of assertion
Correct explanation : It is due to the surface tension of water.
LIGHT
One Mark Questions
I. Choose the best answer:
1. Which of the following curved reflecting surface are called as Spherical mirrors
2. The spherical mirror with a reflecting surface curved inward is called Concave mirror
3. The spherical mirror used as a rear view mirror in the vehicle is Convex mirror
4. The imaginary line passing through the centre of curvature and pole of a spherical mirror is called principal axis
5. The distance from the pole to the focus is called Focal length
6. If the image and object distance is same, then the object is placed at C
7. If the focal length of a spherical mirror is 10 cm, what is the value of its radius of curvature? 20 cm
II. Fill in the blanks:
1. The spherical mirror used in a beauty parlour as make – up mirror is Concave mirror
2. Geometric centre of the spherical mirror is pole
3. Nature of the images formed by a convex mirror is smaller, virtual & erect
4. The mirror used by the ophthalmologist to examine the eye is concave mirror
5. It the angle of incidence is 45°, then the angle of reflection is 45°
6. If an object is placed between two mirrors which are parallel to each other, then the number of images formed is infinite
III. Match the following
1. Convex mirror - Rear-view mirror
2. Parabolic mirror - Radio telescopes
3. Regular reflection - Plane mirror
4. Irregular reflection - Wall
MATTER AROUND US
One Mark Questions
I. Choose the best answer:
1. The liquid metal used in thermometers is Mercury
2. The Pictorial symbol for water given by the alchemists was
3. Which one of the element name not derived from planet? Uranium
4. Symbol of Mercury is Hg
5. A form of non – metal which has high ductility is Carbon
6. The property which allows metals to be hammered into their sheets is Malleability
7. The non – metal which conduct current is Carbon
8. Pencil lead contains Graphite
9. Identity the state of matter based on the arrangement of the molecules
A – Gas, B – Solid, C - Liquid
II. Fill in the blanks:
1. The element which possess character of both metals and non – metals are called Metalloids
2. The symbol of Tungsten W
3. Melting point of most metals is higher than non – metal.
4. Water contains hydrogen and oxygen element.
5.Silicon is the used in semiconductor.
III. Match the following:
1.
1. Iron -Sewing needle
2. Copper- For making wires
3. Tungsten -Making the filament of a bulb
4. Boron As a fuel for ignition in rockets.
2.
1. Atom- building block of matter
2. Element- atoms of the same kind
3. Compound -atoms of different kinds
4. Molecule -smallest unit of a substance
HEAT
I. Choose the best answer
1. Heat is a form of thermal energy
2. If you apply some heat energy to a substance, which of the following can take place in it? Expansion, Increase in temperature, Change of state
3. Which of the following substances will absorb more heat energy? Solid,
Liquid, Gas
4. If you apply equal amount of heat to a solid, liquid and gas individually, which of the following will have more expansion? Gas
5.The process of converting a liquid into a solid is called freezing
6.Conduction is the heat transfer which takes place in a solid, liquid, gas
II. Fill in the blanks:
1. A calorimeter is a device used to measure the heat capacity of water
2. Specific heat capacity is defined as the amount of heat required to raise the temperature of 1 kg of a substance by 1°C.
3. A thermostat is a device which maintains temperature of an object constant
4.The process of converting a substance from gas to solid is called deposition
5.If you apply heat energy, the temperature of a system will increase
6. If the temperature of a liquid in a container is decreased, then the inter Atomic distance will decrease
III. State True or False. If false, correct the statement
1.The applied heat energy can be realized as an increase in the average kinetic energy of the molecules. True.
2.The dimensions of a substance are increased if the temperature of the substance is decreased. False.
Correct statement: The dimensions of a substance are increased if the the temperature of the substance has increased.
3.The process of converting a substance from solid to gas is called condensation. False
Correct statement: The process of converting a substance from solid to gas is called sublimation
4.Convection is the process by which the thermal energy flows in solids. False
Correct statement: Convection is the process by which the thermal energy flows in liquids and gases.
5.The amount of heat gained by a substance is equal to the product of its mass and latent heat. True
6.In a thermos flask, the silvered walls reflect and radiate the heat to the outside.
False .Correct statement: In a thermos flask, the silvered walls reflect radiated heat back to the liquid in the bottle.
III. Match the following
1. Conduction - Solid
2.Convection - Liquid
3. Radiation - Gas
4. Sublimation - Solid to gas
5. Condensation - Gas to liquid
V. Consider the statements given below and choose the correct option:
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of the assertion.
(c) If the assertion is true, but the reason is false.
(d) If the assertion is false, but the reason is true.
1.Assertion : Radiation is a form of heat transfer which takes place even in vacuum.
Reason : The thermal energy is transferred from one part of a substance to another part without the actual movement of the atoms or molecules.
Answer:
(b) Both assertion and reason are true, but reason is not the correct explanation of the assertion.
2.Assertion : A system can be converted from one state to another state.
Reason : It takes place when the temperature of the system is constant.
Answer: (a) Both assertion and reason are true and the reason is the correct explanation of the assertion.
CHANGES AROUND US
One Mark Questions
I. Choose the best answer:
1. Burning of paper is a Chemical change.
2. The burning of matchstick is an example for chemical reaction based on Contact
3. Iron metal undergoes rusting.
4. The pigment responsible for browning of apples is Melanin
5. Brine is a concentrated solution of Sodium chloride
6. Limestone contains Calcium carbonate mainly.
7. Which of the following factor induces electrolysis? Electricity
8. In Haber’s process of producing ammonia is used as a catalyst. Iron
9. Dissolved gases like sulphur dioxide, nitrogen oxides in rain water causes Acid rain
10. Carbon dioxide is responsible for Global warming.
II. Fill in the blanks:
1. Photosynthesis is a chemical reaction that takes place in presence of Iron objects undergo rusting when exposed to and Sunlight
2. Iron objects undergo rusting when exposed to Water and oxygen
3. Ammonia is the basic material to manufacture urea.
4. Electrolysis of Brine solution gives Chlorine and hydrogen gases.
5. Catalyst is a chemical substance which alters the speed of a chemical reaction.
6. Polyphenol oxidase is the enzyme responsible for browning of vegetables, fruits.
III. Write True Or False for the following:
1. A chemical reaction is a temporary reaction. False.
Correct statement:
A chemical reaction is permanent.
2. Decomposition of lead nitrate is an example for chemical reaction caused by light. True
3. Formation of slaked lime from quicklime is a endothermic reaction. False.
Correct statement:
Formation of slaked limed from quicklime is a exothermic reaction.
4. CFC is a pollutant. True.
5. Light energy may come out due to chemical reactions. True
IV. Match the following:
1.
A B
1. Rusting - Iron
2. Electrolysis Brine
3. Thermolysis - Decomposition of limestone
4. Food -photosynthesis
5. Catalysis -Haber’s process
2.
A B
1. Rancidity - fish
2. Ozone -Oxygen
3. Tarnishing-Chemical reaction
4. Yeast - Biocatalyst
5. Calcium Oxide - Decomposition
AIR
I. Choose the best answer:
1. Which of the following is true about oxygen? Supports burning
2. Aerated water contains carbon dioxide
3. Solvay process is a method to manufacture sodium carbonate
4. Carbon dioxide with water changes blue litmus to red
5. Which of the following is known as azote? Nitrogen
II. Fill in the blanks:
1. Oxygen is called as vital life.
2. Nitrogen is lighter than air.
3. Nitrogen is used as a fertilizer.
4. Dry ice is used as a refrigerant
5. The process of conversion of iron into hydrated form of oxides is called rusting.
III. Match the following:
1. Nitrogen - Fertilizer
2. Oxygen - Respiration in living animals
3. Carbon dioxide - Fire extinguisher
4. Dry ice - Refrigerator
Microorganisms
I. Multiple choice questions
1. Micro organisms are measured in micron
2. Shows both living and non-living characteristics Virus
3. Bacteria is a prokaryotic micro organisms.
4. Based on shape, the bacteria are classified into 4 types.
5. Common cold in human is caused by influenza
II. Fill in the blanks
1. Penicillin is prepared from a mold called Penicillium.
2. Prions are the infectious protein particles.
3. The infecting virus particle found outside the host cell is Virion
4. Micro organism can be seen with the help of a Microscope
5. Bacteria, which has a flagellum at one end is classified as Monotrichous
III. True or False
1. Diseases causing microorganisms are called pathogens. True.
2. Female Anopheles mosquito is a carrier of dengue virus. False.
Correct statement:
Female Anopheles mosquito is a carrier of malaria.
3. Chicken pox is a communicable disease. True.
4. Citrus canker is transmitted by insects. True.
Correct statement:
Citrus canker is transmitted by air and water
5. Yeast is used in the large scale production of alcohol. True.
IV. Match the following
1. Nitrogen fixing bacteria - Rhizobium
2. Tuberculosis - Bacteria
3. Kuru - Prion
4. Probiotics - Lactobacillus acidophilus
5. Edward Jenner - Vaccine
V. Assertion & Reason
1. Assertion : Malaria is caused by Protozoa.
Reason : The disease is transmitted by mosquito.
Answer: Both Assertion and Reason are true and Reason is the correct
explanation of Assertion
2. Assertion : Algae are heterotrophic.
Reason : They don’t have chlorophyll.
Answer: Both Assertion and Reason are false
VI. Answer very briefly:
1. Write the name of any nitrogen fixing bacteria.
Rhizobium.
2. Name the bacteria used in the production of vinegar.
Acetobacter aceti.
3. Write the names of any three protozoans.
Amoeba, Plasmodium, Paramecium.
4. Who discovered penicillin?
Alexander Flemming.
5. Which diseases can be prevented by vaccination?
Small pox, polio, measles, mumps, rubella, tuberculosis.
PLANT KINGDOM
I. Choose the correct answers
1. Solanum trilobatum is the binomial name of Thoothuvalai. Here the word ‘Solanum’ refers to Genus
2. Floridean starch is a reserve food material of Rhodophyceae
3. Volvox is an example for colonial form of algae.
4. One of the following is an edible mushroom is Agaricm
5. Plants that prevent soil erosion are plants.
6. The first in land plants are Pteridophytes
7. The well – developed sporophytic plant body is seen in Gymnosperms
8. Binominal Nomenclature was first introduced in the year of 1623
9. Penicillin is an antibiotic, which is extracted from Fungi
II. Fill in the blanks
1. The word‘Taxonomy’is derived from Greek
2. Binomial Nomenclature was first introduced by Gaspard Bauhin
3. The book “Genera Plantarum” was written by Bentham and Hooker
4. Monocotyledon seeds bear only One cotyledon.
5. Brown algae belongs to Phaeophyceae class.
6. Agar Agar is obtained from Red algae.
7. The reserve food material of fungi are Glycogen and oil
8. The first true land plant is Pteridophyte
9. Xylem and phloem are absent in Bryophyte plants.
10. Reticulate venation is present in Dicot plants.
III. True or False
1. In polypetalae, the petals are free.True.
2. Binomial name should contains more than two words. False.
Correct statement:
Binomial name should contain two words.
3. Artificial system of classification is based on the vegetative characters of the plant. False.
Correct statement:
Artificial system of classification is based on the morphological characters of the plant.
4. Cell wall of fungi is made up of chitin. True.
5. Pinus is a closed seeded plant. False.
Correct statement:
Pinus is a naked seeded plant.
6. All bryophytes are hydrophytes. False.
Correct statement:
All bryophytes are amphibians.
7. Dicotyledons have well developed characters than the monocotyledons.
False.
Correct statement:
Monocotyledons have well developed characters than the dicotyledons.
8. Mosses are the well developed plant in bryophytes. True.
9. The dominant phase of the bryophytes is sporophytes. False.
Correct statement:
The dominant phase of the bryophytes is gametophyte.
10. The dominant phase of the pteridophytes is diploid(2n). True.
IV. Match the following
1. Cyanophyceae - Blue green algae
2. Chlorophyceae - Green algae
3. Phaeophyceae - Brown algae
4. Rhodophyceae - Red algae
ORGANIZATION OF LIFE
I. Choose the correct answers
1. Sclera is tough and thick white sheath that protect the inner parts of the eye.
2. Stem cells are specialised cells that can be transformed into any kind of cells.
3. Maintenance of constant internal environment of the body is known as Homeostasis
4. In the absence of oxygen, glucose is broken down into Lactic acid
5. The process of air passing in and out the lungs is called Breathing
6. Osmosis is the movement of water molecules from a Higher concentration
to a region of lower concentration
7. The erythrocyte is placed in Hypotonic solution which has lesser concentration of solutes and greater concentration of water than in the cytoplasm.
II. Fill in the blanks
1. Cell is the structural and functional unit of living organisms.
2. The largest cell is egg of an Ostrich
3. Fermentation is a good example for anaerobic respiration.
4. Optic nerve is located at the end of the eyes behind the retina.
5. The size of the cells are measured in units of Microns
III. Match the following.
1. Carbohydrates - Glucose
2. Glucose - CO2, Water and Heat
3. Protein - Amino acid
4. Amino acids - Enzymes, hormone, protein
5. Fatty acids - Cholesterol and other steroid
IV. Write true or False. If false, give the correct answer
1. In hypotonic condition, concentration of the external and the internal solution of the organism are same. False.
Correct statement:
The concentration of external solution is less compared to concentration of internal solution of the organism.
2. Diffusion is the movement of particles from an area of lower concentration to higher concentration.False.
Correct statement:
Diffusion is the movement of particles from an area of higher concentration to lower concentration.
3. Human beings are warm blooded in nature.True.
4. The larynx has fold of tissue which vibrate with the passage of air to produce. True.
5. Aqueous humour plays an important role in maintaining the shape of the eye. True.
