Case Study Questions Class 10 Science CBSE Chapter Wise

Chemical Reactions and Equations Case Study Questions Class 10 Science

I. Clean a magnesium ribbon about 2 cm long by rubbing it with sandpaper. Hold it with a pair of tongs. Burn it using a spirit lamp or burner and collect the ash so formed in a watch-glass. 

Question. What is the chemical name of the powder obtained in the activity?
(a) magnesium carbonate
(b) magnesium oxide
(c) magnesium sulphide
(d) magnesium chloride

Answer: B

Question. Which compound is formed when the powder obtained reacts with water?
(a) Magnesium sulphate
(b) Magnesium oxide
(c) Magnesium carbonate
(d) Magnesium hydroxide

Answer: D

Question. Magnesium ribbon is rubbed before burning because it has a coating of
(a) basic magnesium carbonate
(b) basic magnesium oxide
(c) basic magnesium sulphide
(d) basic magnesium chloride

Answer: A

Question. What is the colour of magnesium ribbon?
(a) White
(b) Black
(c) Grey
(d) Yellow

Answer: C

II. Take a plastic mug, drill two holes at its base and insert carbon electrodes. Connect these electrodes to a 6 volt battery. Fill the mug with water such that the electrodes are immerse(d) Add a few drops of dilute sulphuric acid to the water. Take two test tubes filled with water and invert them over the two carbon electrodes. Switch on the current and leave the apparatus undisturbed for some time.

Question. Where is hydrogen gas collected?
(a) Anode
(b) Cathode
(c) At both electrodes
(d) Hydrogen gas is not evolved in this activity

Answer: B

Question. Which of the following is an endothermic process?
(a) Dilution of sulphuric acid
(b) Condensation of water vapours
(c) Respiration in human beings
(d) Electrolysis

Answer: D

Question. What is the ratio in which hydrogen and oxygen are present in water by volume?
(a) 1:2
(b) 1:1
(c) 2:1
(d) 1:8

Answer: C

Question. Which electrodes are used in this activity?
(a) Graphite
(b) Diamond
(c) Copper
(d) Coke

Answer: A

III. Take about 2 g ferrous sulphate crystals in a dry boiling tube. Heat the boiling tube over the flame of a burner or spirit lamp. In this reaction you can observe that a single reactant breaks down to give simpler products. This is a decomposition reaction.
Ferrous sulphate crystals (FeSO₄, 7H₂O) lose water when heated and the colour of the crystals changes. It then decomposes to ferric oxide (Fe₂O₃), sulphur dioxide (SO₂) and sulphur trioxide (SO₃). Ferric oxide is a solid, while SO₂ and SO₃ are gases. 

Question. What compound is formed when sulphur dioxide is passed through water?
(a) Sulphuric acid
(c) Hydrogen Sulphide
(b) Sulphurous acid
(d) Sulphur trioxide

Answer: C

Question. What can we observe in this activity?
(a) Water vapor is evolved
(b) Change in colour
(c) Smell of burning sulphur
(d) All of the above.

Answer: D

Question. What is the colour of iron oxide?
(a) Brown
(c) Yellow
(b) Grey
(d) White

Answer: A

IV. Read the following and answer the questions
The double displacement reaction is a type of chemical reaction. where two compounds react and the cation and anion of the two reactants 6 places forming 2 new products. The ionic compounds considered as reactants are water soluble. One of the products is formed as a precipitate or as a gas which is water soluble.

Question. Which metallic spoon can be used to stir Lead nitrate solution ?
(a) Sodium
(b) Silver
(c) Iron
(d) Aluminum

Answer: C

Question. The reaction between lead nitrate and potassium iodide is an example of.
(a) Combination reaction
(b) Decomposition Reaction
(c) Displacement reaction
(d) Double displacement reaction.

Answer: C

Question. What was the color of the precipitate formed when Lead nitrate reacts with Potassium iodide ?
(a) Blue
(b) Red
(c) Yellow
(d) Orange

Answer: B

V. We have observed that iron articles are shiny when new, but get coated with a reddish brown powder when left for some time. This process is commonly known as rusting of iron.
Some other metals also get tarnished in this manner. Have you noticed the colour of the coating formed on copper and silver? When a metal is attacked by substances around it such as moisture, acids, et(c), it is said to corrode and this process is called corrosion.

Question. If a metal under goes uniform corrosion it becomes
(a) Thicker
(b) Perforated
(c) Thinner
(d) None of the above

Answer: C

Question. The chemical formula of rust is
(a) Fe2O₃
(b) Fe3o₄
(c) Fe2O₃ XH₂O
(d) Fe3O₄. XH₂O

Answer: C

Question. Which of the following metal is highly corrosive ?
(a) Zinc
(b) Aluminum
(c) Gold
(d) Silver

Answer: B

Acids Based And Salts Case Study Questions Class 10 Science 

I. There are many substances which are used to detect the solutions as acidic or basic. They are called Acid-Base indicators. Depending upon the property of the indicator, we have different groups of Acid-Base indicators. Some indicators show different colours in acidic or basic medium and some indicators give different odours in acidic and basic medium. These indicators are either extracted from the plants or synthesised in the laboratory or industry.

Question. Which one of the following can be used as an acid-base indicator by visually impaired student?
(a) Turmeric
(b) Hibiscus
(c) Vanilla
(d) Litmus

Answer: C

Question. Select the incorrect option.
Indicator Colour in acidic medium Colour in basic medium
(a) Litmus (Purple) Red Blue
(b) Phenolphthalein (Colourless) Pink Colourless
(c) Red cabbage extract (Purple) Red Green
(d) Methyl orange (Orange) Red Yellow

Answer: B

Question. Which of the following will turn red litmus blue?
(a) Amla juice
(b) lemon juice
(c) Soft drink
(d) Baking soda

Answer: D

Question. A solution turns blue litmus red, the pH of the solution is likely to be-
(a) 6
(b) 7
(c) 8
(d) 9

Answer: A

II. Tajmahal, the seventh wonder of the world, is made of white stone. This white stone contains the same substance ‘A’ that is present in chalk powder and lime-stone. It is turning yellow due to polluted air. If it is cleaned by an acidic cleaner, a gas ‘B’ is released, which when passed through a solution ‘C’, forms the same substance which is present in the white stone that was used to make Tajmahal. 

Question. Solution C is-
(a) CaCl₂
(b) CaCO₃
(c) Ca(OH)₂
(d) CaSO₄

Answer: C

Question. What is the nature of the substance A?
(a) Acidic
(b) Basic
(c) Neutral
(d) None

Answer: B

Question. The substance A is-
(a) Ca₃CO₂
(b) CaCO₃
(c) Ca(OH)₂
(d) CaSO₄

Answer: B

Question. Gas B is-
(a) Hydrogen
(b) Nitrogen
(c) Chlorine
(d) Carbon di oxide

Answer: D

III. A scale for measuring hydrogen ion concentration in a solution, called pH scale has been developed. The p in pH stands for ‘potenz’ in German, meaning power. On the pH scale we can measure pH from 0 to 14. pH should be thought of simply as a number which indicates the acidic or basic nature of a solution. Higher the hydronium ion concentration, lower is the pH value.

Question. A basic solution could have a pH of-
(a) 3
(b) 5
(c) 7
(d) 9

Answer: D

Question. The table provides the pH of four solutions P, Q, R and S.
Solution pH value
P 2
Q 9 
R 5
S 11
Which of the following correctly represents the solutions in increasing order of their hydronium ion concentration?
(a) P > Q > R > S
(b) P > S > Q > R
(c) S < Q < R < P
(d) S < P < Q < R

Answer: C

Question. Which one of the following will have the highest hydrogen ion concentration?
(a) pH = 1.1
(b) pH = 2.2
(c) pH = 3.3
(d) pH = 4.4

Answer: A

Question. How is the hydrogen ion concentration and pH related to each other?
(a) They are inversely proportional.
(b) They are directly proportional.
(c) They are equal.
(d) They have no relation.

Answer: A

IV. Bleaching powder is a pale yellowish powder. It is soluble in water but due to the presence of impurities, we never observe a clear solution. Its chemical formula is Ca(OCl₂) with its chemical name as Calcium hypochlorite. Bleaching powder is also called calcium chlorohypochlorite because it is considered as a mixed salt of hydrochloric acid and hypochlorous acid.

Question. One of the following cannot be considered as the use of bleaching powder
(a) It is an oxidising agent.
(b) it is used for disinfecting water.
(c) it bleaches cotton and linen in the textile industry.
(d). it releases Oxygen gas on heating which can be used for aeration of water bodies.

Answer: D

Question. The compound lime water that is used in the manufacture of bleaching powder is
(a) Clear solution of Ca(OH)₂.
(b) Milky Suspension of Ca(OH)₂.
(c) Clear solution of CaCl₂.
(d) Clear solution of CaCO₃.

Answer: A

Question. One of the products obtained during the electrolysis of aqueous Sodium Chloride(brine) used in the preparation of Bleaching powder is.
(a) Sodium metal at cathode
(b) Hydrogen gas
(c) Chlorine gas
(d) Slaked lime.

Answer: C

V. Water of crystallisation is the fixed number of water molecules present in one formula unit of a salt. water(s) of crystallization or water(s) of hydration are water molecules that are present inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions. A salt with associated water of crystallization is known as a hydrate.

Question. The formula of Plaster of Paris is CaSO₄. ½ H₂O, it is to be noted that half water molecule is shown to be attached as water of crystallisation. This indicates that
(a) Only half water molecule is present in Calcium Sulphate crystal
(b) Two formula units of Calcium Sulphate share one molecule of water.
(c) Two formula units of calcium Sulphate share two molecules of water
(d) Two formula units of Calcium Sulphate share one and a half molecules of water.

Answer: B

Question. Which of the following salt does not contain water of crystallisation?
(a) Blue Vitriol
(b) Baking Soda
(c) Washing Soda
(d) Gypsum.

Answer: B

Question.The temperature at which Gypsum (CaSO₄ . 2H₂O) into Plaster of Paris(CaSO₄.1/2 H₂O
(a) 373 K
(b) 273 K
(c) 374 K
(d) 375 K

Answer: A

Metals And Non-Metals Case Study Questions Class 10 Science 

I. On the basis of reactivity of different metals with oxygen, water and acids as well as displacement reactions, the metals have been arranged in the decreasing order of their reactivities. This arrangement is known as activity series or reactivity series of metals.
The basis of reactivity is the tendency of metals to lose electrons. If a metal can lose electrons easily to form positive ions, it will react readily with other substances. Therefore, it will be a reactive metal. On the other hand, if a meal loses electrons less rapidly to form a positive ion, it will react slowly with other substances. Therefore, such a metal will be less reactive.

Question. Hydrogen gas is not evolved when a metal reacts with nitric aci(d) It is because HNO, is a strong oxidising agent. It oxidises the H, produced to water and itself gets reduced to any of the nitrogen oxides (N,O, NO, NO₂). But and ___react with very dilute HNO3 to evolve H2 gas.
(a) Pb, Cu
(b) Na, K
(c) Mg, Mn
(d) Al, Zn

Answer: C

Question. Which of the following metals reacts vigorously with oxygen?
(a) Zinc
(b) Magnesium
(c) Sodium
(d) Copper

Answer: C

Question. Which of the following metal is less reactive than hydrogen?
(a) Copper
(b) Zinc
(c) Magnesium
(d) Lead

Answer: A

Question. Which of the following represents the correct order of reactivity for the given metals?
(a) Na>Mg>Al>Cu
(b) Mg>Na>Al>Cu
(c) Na>Mg>Cu>Al
(d) Mg > Al > Na > Cu

Answer: A

II. Ionic compound is a chemical compound in which ions are held together by ionic bonds.
An ionic bond is the type of chemical bond in which two oppositely charged ions are held through electrostatic forces. We know that, metal atoms have loosely bound valence electrons in their valence shell and non-metal atoms need electrons in their valence shell to attain noble gas configuration. The metal atom loses the valence electrons while non-metal atom accepts these electrons. By losing electrons, metal atoms change to cations and by accepting electrons, non-metals form anions. Ionic compounds are generally solid and exist in the form of crystal. They have high melting and boiling points.

Question. Ionic compounds are soluble in _____________.
(a) Kerosene
(b) Petrol
(c) Water
(d) None of these

Answer: C

Question. Which of the following statements is correct about ionic compounds?
I. They conduct electricity in solid state.
II. They conduct electricity in solutions.
III. They conduct electricity in molten state.
(a) I only
(b) II only
(c) III only
(d) II and III only

Answer: D

Question. Which of the following can change to a cation?
(a) Fluorine
(b) Oxygen
(c) Potassium
(d) Neon

Answer: C

Question. Which of the following can change to an anion?
(a) Iodine
(b) Magnesium
(c) Calcium
(d) Xenon

Answer: A

Question. Select the incorrect statement.
(a) Ionic compounds are generally brittle
(b) Ions are the fundamental units of ionic compounds
(c) Formation of ionic bonds involve sharing of electrons
(d) NaCl is an ionic compound.

Answer: C

III. The arrangement of metals in a vertical column in the decreasing order of their reactivities is called the reactivity series or activity series of metals. The most reactive metal is at the top position of the reactivity series. The least reactive metal is at the bottom of the reactivity series. Hydrogen, though a non-metal, has been included in the activity series of metals only for comparison. Apart from it, the hydrogen atom also has tendency to lose its valence electron and form cation which behaves like metal H→H+ + e−

Question. The most reactive metal is
(a) potassium
(b) barium
(c) zinc
(d) calcium

Answer: A

Question. Which of the following metals does not react with water at all?
(I) Sodium
(II) Copper
(III) Aluminium
(IV) Gold
(a) I and III only
(b) IV only
(c) II and IV only
(d) I, II, III and IV

Answer: C

Question. The metal which does not liberate hydrogen gas after reacting with acid is
(a) zinc
(b) lead
(c) iron
(d) gold

Answer: D

Question. Which metal can be displaced by copper from its salt solution?
(a) Zinc
(b) Silver
(c) Iron
(d) Lead

Answer: B

Question. An element 'X after reacting with acids liberates hydrogen gas and can displace lead and mercury from their salt solutions. The metal 'X is
(a) copper
(b) gold
(c) calcium
(d) hydrogen.

Answer: C

IV. Metals as we know, are very useful in all fields, industries in particular. Non-metals are no less in any way. Oxygen present in air is essential for breathing as well as for combustion.
Non-metals form a large number of compounds which are extremely useful, e.g., ammonia, nitric acid, sulphuric acid, etc.
Non-metals are found to exist in three states of matter. Only solid non-metals are expected to be hard however, they have low density and are brittle. They usually have low melting and boiling points and are poor conductors of electricity.

Question. Which of the following non-metals is a liquid?
(a) Carbon
(b) Bromine
(c) Iodine
(d) Sulphur

Answer: B

Question. Hydrogen is used
(a) for the synthesis of ammonia
(b) for the synthesis of methyl alcohol
(c) nitrogenous fertilizers
(d) all of these

Answer: D

Question. Generally, non-metals are bad conductors of electricity but 'X' which is a form of carbon is a good conductor of electricity and is an exceptional non-metal. 'X 'is
(a) diamond
(b) graphite
(c) coal
(d) c o ke.

Answer: B

Question.____________ is a non-metal but is lustrous
(a) Phosphorus
(b) Sulphur
(c) Bromine
(d) Iodine

Answer: D

Question. Which of the following is known as 'King of chemicals'?
(a) Urea
(b) Ammonia X
(c) Sulphuric acid
(d) Nitric acid

Answer: C

V. When a silvery grey powder of a solid (A) is mixed with a powder of solid (B) no reaction occurs. But if the mixture is ignited and lighted using magnesium ribbon a reaction occurs with evolution of large amount of heat forming product which settles down as liquid metal and the solid product(D) formed floats on the liquid (C). (C)in solid form reacts with moisture to form rust. The amount of heat generated during the reaction is so high that the reaction is used in welding of electric conductors, joints in railway tracks. Based on this information, answer the following questions.

Question. Amphoteric oxides are
(a) metal oxides which do not react with acids but react with bases
(b) metal oxides which reacts with both acids as well as bases
(c) metal oxides which reacts with acids but do not react with bases
(d) metal oxides which shows no reaction with either acids or bases

Answer: B

Question. Which of the following is amphoteric in nature?
(a) both aluminium oxide and zinc oxide
(b) Only Zinc oxide
(c) Only Aluminium oxide
(d) Neither of them

Answer: A

Question. Identify A and C?
(a) A- Al and C- Fe
(b) A-Fe and C—Al
(c) A-Mg and C -Al
(d) A-Al and C -Cu

Answer: A

Question. Identify B and D which are oxides of
(a) B- Fe , D- Al
(b) B- Mg, D-Al
(c) B- Al , D- Cu
(d) B-Al , D -Fe

Answer: A

Life Processes Case Study Questions Class 10 Science

I. There is a range of strategies by which the food is taken in and used by the organisms in heterotrophic nutrition. Some organisms breakdown the food material outside the body and then absorb it. Others take in whole material and break it down inside their bodies. What can be taken in and broken down depends on the body design and functioning. Some others derive nutrition from plants and animals without killing them.

Question. Which of the following is an example of saprotroph.
(a) Cuscuta
(b) Sugarcane
(c) Bread mould
(d) Amoeba

Answer: A

Question. Taking in whole material and breaking it down inside the body is
(a) Parasitic nutrition
(b) Holozoic nutrition
(c) Saprophytic nutrition
(d) Symbiosis

Answer: B

Question. Heterotrophic nutrition involves
(a) Production of simple sugar from inorganic compounds
(b) Utilisation of chemical energy to prepare food
(c) Utilisation of energy obtained by plants
(d) All of these

Answer: C

Question. Organisms which derive nutrition from plants and animals without killing them.
(a) Parasites
(b) Saprophytes
(c) Heterotrophs
(d) Autotrophs

Answer: A

Question. In which part of amoeba complex food particles are broken down into simpler ones.
(a) Cytoplasm
(b) Pseudopodia
(c) Nucleus
(d) Food vacuole

Answer: D

II. 

Question. The enzyme that is released by label A
(a) Tripsin
(b) Amino acids
(c) Amylase
(d) Intestinal juices

Answer: C

Question. The movements that occur along part B to push the food forwar(d)
(a) Rotation
(b) Peristalsis
(c) Flexion
(d) Protrusion

Answer: B

Question. Which of these correctly represent the labels B C D and E
(a) Pancreas , Oesophagus , Stomach , Liver
(b) Oesophagus , Liver , Stomach , Pancreas
(c) Stomach , Liver , Oesophagus , Pancreas
(d) Oesophagus , Pancreas , Liver , Stomach

Answer: B

Question. Villi are present in
(a) D
(b) E
(c) F
(d) A

Answer: C

Question. In case of diarrhoea, which major process does not takes place normally in region G?
(a) Absorption of food
(b) Absorption of water
(c) Secretion of hormones
(d) Removal of waste material

Answer: B

III. 

Question. Type of respiration seen during fermentation
(a) Aerobic
(b) Anaerobic
(c) Reduction
(d) Oxidation

Answer: B

Question. End product of Aerobic respiration
(a) NADH
(b) Oxygen
(c) ATP
(d) CO₂ +ATP+H₂O

Answer: D

Question. The pathway of respiration common in all living organisms is X ; it occurs in the Y and the products formed are two molecules of Z . Identify X Y Z and select the correct answer.
           X                 Y                     Z
(a) Glycolysis Mitochondria Pyruvic acid
(b) Glycolysis Cytoplasm Pyruvic acid
(c) Citric acid cycle Cytoplasm Phosphate
(d) Kreb’s cycle Mitochondria Acetyl CoA

Answer: B

Question. During vigorous physical exercise, lactic acid is formed from glucose inside the muscle cells because
(a) there is lack of oxygen
(b) there is lack of water
(c) there is excess of carbon dioxide
(d) none of the above

Answer: A

Question. Amount of energy released is more during
(a) Anaerobic respiration
(b) Fermentation
(c) Aerobic respiration
(d) Reduction

Answer: C

IV. Blood transport food, Oxygen and waste materials in our bodies. It consists of plasma as a fluid medium. A pumping organ [heart]is required to push the blood around the body.The blood flow through the chambers of heart in a specific manner and direction .While flowing throughout the body, blood exert a pressure against the wall or a vessel.

Question. Which of the following statements are true about human heart ?
(a) It is a hollow muscular organ
(b) It is four chambered having three auricles and one ventricle.
(c) It has different chambers to prevent Oxygen rich blood from mixing with the blood containing Carbondioxide
(d) BOTH A & C

Answer: D

Question. Study the table below and select the row that has correct information.
BODY FLUID CONTENTS
(a) Blood plasma + RBC+
      WBC + platelets
(b) Plasma Blood -- RBC
(c) Lymph Plasma +RBC
(d) Serum Plasma + RBC +WBC

Answer: A

Question. Oxygenated blood from lungs enters left atrium through
(a) vena cava
(b) pulmonary artery
(c) pulmonary vein
(d) Aorta

Answer: C

Question. The rate of blood flow in the capillaries is very low because capillaries are
(a) very narrow and have high resistance
(b) Much wide and have low resistance
(c) Very narrow and have low resistance
(d) Much wide and have high resistance

Answer: A

V. Our body needs to remove the wastes that build up from cell activities and from digestion . If these wastes are not removed , then our cells can stop working and we can get very sick.The organs of excretory system consists of a pair of kidneys, a pair of ureters , a urinary bladder and a urethra. Each kidney is made up of nearly one million complex tubular structures called nephrons. The formation of urine involves various processes that takes place in the different parts of the nephrons. Each nephron consists of a cup- shaped upper end called Bowman’s capsule containing a bunch of capillaries called glomerulus. Bowman’s capsule leads to tubular structure, proximal convoluted tubule, loop of Henle and distal convoluted tubule which ultimately joins the collecting tubule.

Question. The out line of principal events of urination is given below in random order.
I) stretch receptors on the wall of urinary bladder send signals to the CNS.
II) The bladder fills with urine and become distended.
III) Micturition
IV) CNS passes on motor messages to initiate the contraction of smooth muscles of bladder and simultaneous relaxation of urethral sphincter. The correct sequence of the events is
(a) I → II → III→ IV
(b) IV → III → II→ I
(c) II → I→ IV → III
(d) III → II→ I→ IV

Answer: C

Question. Urine formation occurs through
(a) Ultrafiltration, reabsorption, secretion and osmosis.
(b) secretion, osmosis, ultrafiltration and reabsorption.
(c) only filtration and absorption .
(d) only osmosis and secretion.

Answer: A

Question. The following substances are the excretory products in animals. Choose the least toxic form.
(a) Urea
(b) Uric acid
(c) Ammonia
(d) Carbondioxide

Answer: B

Question. Glomerular filtrate is first collected by
(a) Distal convoluted tubule
(b) proximal convoluted tubule
(c) Bowman’s capsule
(d) loop of Henle

Answer: C

Light Reflection & Reflection Case Study Questions Class 10 Science

I. An image formed in a convex mirror is always virtual, erect and smaller in size whatever be the position of the object. However in a concave mirror the image may be real or virtual:
erect or inverted :smaller or bigger in size than the object. This would depend upon the distance of the object from the mirror.

Question. Which of the mirrors has larger field of view ?
(a) Convex
(b) Concave
(c) plane
(d) all have same field of view

Answer: A

Question. Real or virtual image of an object formed by a concave mirror depends on
(a) Size of mirror
(b) Polish of mirror
(c) Distance of object from the mirror
(d) All of these

Answer: C

Question. A Concave mirror is used as reflector in
(a) Torches
(b) Search lights
(c) Head lights of motor vehicles
(d) All the above

Answer: D

Question. In street lamps,the reflector used is a
(a) Convex mirror
(b) Concave mirror
(c) Plane mirror
(d) None of these

Answer: A

II. The image of an object formed by a convex lens may be real/virtual: erect/inverted; smaller/larger than the object. It would depend upon distance of the object from the lens. however, the image of an object formed by a concave lens is always virtual, erect and smaller in size than the object.

Question. Where should an object be placed in front or a convex lens to obtain image of the size of the object ?
(a) At focus F
(b) At 2 F
(c) Beyond 2 F
(d) None of these

Answer: C

Question. To obtain an image smaller than the size of the object, we may used a
(a) Convex lens only
(b) Concave lens only
(c) Either a convex lens or a concave lens
(d) Cannot say

Answer: B

Question. Question: to obtain image of an object on a screen jwe require a
(a) Convex lens
(b) Concave lens
(c) Concave lens of large focal length
(d) Concave lens of small focal length

Answer: A

Question. Where an object should be placed in front of a concave lens to obtain a virtual image of the object?
(a) Infinity
(b) Principal focus
(c) Very close to the lens
(d) Any distance from the lens

Answer: D

III. The scattering involves bouncing off of light by atoms/molecules of the medium through which they are travelling. Most of the beautiful phenomena like blue colour of sky, white colour of clouds, red hues of sunrise and sunset have been explained in terms of scattering of light. Lord Rayleigh studied elastic scattering and established that intensity of scattered light (Is) varies inversely as the fourth power of wavelength (ℷ) of incident light. The only condition for Rayleigh scattering to be valid is that size of scatterer (x) must be much less than the wavelength (ℷ) of light.

Question. In Rayleigh scattering intensity of scattered light (Is) varies inversely as power (n) of wave length (ℷ) of light, where n =
(a) 6
(b) 8
(c) 4
(d) 2

Answer: C

Question. Rayleigh scattering accounts for
(a) Blue colour of sky
(b) White colour of clouds
(c) Red hues of sun rise and sun set
(d) All the above

Answer: B

Question. Rayleigh scattering accounts for
(a) Blue colourof sky
(b) White colour of clouds
(c) Red hues of sunrise and sunset
(d) All the above

Answer: C

Question. The essential condition for rayleigh’s scattering is the size (x) of scatterer must be
(a) Much smaller wave length (ℷ) of light
(b) Much grater then the wave length of light
(c) Equal to wave length of light
(d) Cannot say

Answer: D

The Human Eye And Colourful Word Case Study Questions Class 10 Science

I. The phenomenon of splitting of white light into its seven constituent colors when it passes through a glass prism is called dispersion of white light. The various colors seen are Violet, Indigo, Blue, Green, Yellow, Orange and Re(d) The sequence of colors remembers as VIBGYOR. The band of seven colors is called the spectrum. 

Question. Which Color deviates most in the formation of spectrum of white light by a prism ?
(a) VIOLET
(b) ORANGE
(c) GREEN
(d) RED

Answer: A

Question. The angle between incident ray and emergent ray of a prism is called .
(a) Angle of Refraction
(b)Angle of deviation
(c)Angle of incidence
(d)Angle of emergence

Answer: B

Question. What happens when white light is passed from air to glass prism ?
(a) Reflects back
(b) Bends away from normal
(c) Un deviated
(d) Bends towards normal

Answer: D

II. A collection of suspended water droplets in the atmosphere serves as a refractor of light.
The water represents a medium with a different optical density than the surrounding air. Light waves refract when they cross over the boundary from one medium to another. The decrease in speed upon entry of light into a water droplet causes a bending of the path of light towards the normal. And upon exiting the droplet, light speeds up and bends away from the normal.
The droplet causes a deviation in the path of light as it enters and exits the drop.
There are countless paths by which light rays from the sun can pass through a drop. Each path is characterized by this bending towards and away from the normal.
One path of great significance in the discussion of rainbows is the path in which light refracts into the droplet, internally reflects, and then refracts out of the droplet. The diagram at the right depicts such a path. A light ray from the sun enters the droplet with a slight downward trajectory. Upon refracting twice and reflecting once, the light ray is dispersed and bent downward towards an observer on earth's surface. Other entry locations into the droplet may result in similar paths or even in light continuing through the droplet and out the opposite side without significant internal reflection. But for the entry location shown in the diagram at the right, there is an optimal concentration of light exiting the airborne droplet at an angle towards the ground. As in the case of the refraction of light through prisms with nonparallel sides, the refraction of light at two boundaries of the droplet results in the dispersion of light into a spectrum of colors. The shorter wavelength blue and violet light refract a slightly greater amount than the longer wavelength red light. Since the boundaries are not parallel to each other, the double refraction results in a distinct separation of the sunlight into its component colors. 

Question. When compared to air, medium of water droplet is
(a) Optically rarer
(b) Has same optical density
(c) Optically insignificant when compared to air
(d) Optically denser.

Answer: D

Question. Rainbow can also be observed on a sunny day when an observer looks at the sky through a waterfall or a sprinkler source or through a water fountain with the following condition.
(a) Sun between the observer and the water source.
(b) Sun behind the observer.
(c) Sun behind the water source with observer in the opposite direction.
(d) Position of sun does not affect the formation of rainbow.

Answer: B

Question. The speed of light from sun when enters the water droplet undergoes this phenomenon
(a) its speed decreases
(b) Light gets absorbed in the droplet
(c) it becomes monochromatic
(d) Passes through undeviated

Answer: A

Question. The rainbow formation could be because of the following reasons
(a) light being reflected when entering a droplet of water, then refracted inside on the back of the droplet and refracted again when leaving it.
(b) light being refracted when entering a droplet of water, then reflected inside on the back of the droplet and refracted again when leaving it.
(c) Due to interference of different wavelengths in white light
(d) All scenarios possible.

Answer: B

III. Atmospheric refraction is the phenomenon of bending of light on passing through earth’s atmosphere. As we move above the surface of earth, density of air goes on decreasing. Local conditions like temperature etc. also affect the optical density of earth’s atmosphere. On account of atmospheric refraction, stars seen appear higher than they actual are; advanced sunrise; delayed sunset, oval appearance of the sun at sunrise and sunset; stars twinkle, planets do not.

Question. The sun appears oval shaped or flattened due to
(a) dispersion
(b) scattering
(c) atmospheric refraction
(d) cannot say

Answer: C

Question. Twinkling of stars and non-twinkling of planets is accounted for by
(a) scattering of light
(b) dispersion of light
(c) atmospheric refraction
(d) none of these

Answer: C

Question. Due to atmospheric refraction, apparent length of the day
(a) increases
(b) decreases
(c) remains the same
(d) all of these

Answer: A

Question. Apparent position of the star appears raised due to
(a) atmospheric refraction
(b) scattering of light
(c) both (a) and (b)
(d) none of these

Answer: A

Question. In absence of atmosphere, the colour of sky appears
(a) blue
(b) black
(c) red
(d) yellow

Answer: B

IV. The spreading of light by the air molecules is called scattering of light. The light having least wavelength scatters more. The sun appears red at sunrise and sun set, appearance of blue sky it is due to the scattering of light. The colour of the scattered light depends on the size of particles. The smaller the molecules in the atmosphere scatter smaller wavelengths of light.
The amount of scattering of light depends on the wavelength of light. When light from the sun enters the earth’s atmosphere , it gets scattered by the dust particles and air molecules present in the atmosphere. The path of sunlight entering in the dark room through a fine hole is seen because of scattering of the sunlight by the dust particles present in its path inside the room.

Question. The colour of sky appears blue, it is due to the
(a) refraction of light through the atmosphere
(b) dispersion of light by air molecules
(c) scattering of light by fine dust particles
(d) all of these

Answer: C

Question. To an astronaut in a spaceship , the colour of earth appears
(a) red
(b) blue
(c) white
(d) black

Answer: D

Question. At the time of sunrise and sunset , the light from sun has to travel
(a) longest distance of atmosphere
(b) shortest distance of atmosphere
(c) both (A) and (B)
(d) can’t say.

Answer: A

V. The spreading of light by the air molecules is called scattering of light. The light having least wavelength scatters more. The sun appears red at sunrise and sunset, appearance of blue sky it is due to the scattering of light. The colour of the scattered light depends on the size of particles. The smaller the molecules in the atmosphere scatter smaller wavelengths of light.
The amount of scattering of light depends on the wavelength of light. When light from sun enters the earth’s atmosphere, it gets scattered by the dust particles and air molecules present in the atmosphere. The path of sunlight entering in the dark room through a fine hole is seen because of scattering of the sun light by the dust particles present in its path inside the room.

Question. The colour of sky appears blue, it is due to the
(a) Refraction of light through the atmosphere
(b) Scattering of light by air molecules
(c) Dispersion of light by air molecules
(d) All the above

Answer: B

Question. At the time of sunrise and sunset
(a) Blue colour scattered and red colour reaches our eye
(b) Red colour scattered and blue colour reaches our eye
(c) Green and blue scattered and orange reaches our eye
(d) None of these

Answer: B

Question. To an astronaut in a spaceship, the colour of earth appears
(a) Red
(b) Blue
(c) White
(d) Black

Answer: B

Question. At the time of sunsise and sunset light has to travel
(a) Longest distance of atmosphere
(b) Shortest distance of atmosphere
(c) Both A and B
(d) Cannot say

Answer: A

 PRACTICALS

First Term

1. To find the pH of the following samples by using pH paper/universal indicator:

 a. Dilute Hydrochloric Acid

 b. Dilute NaOH solution

 c. Dilute Ethanoic Acid solution

 d. Lemon juice

 e. Water

 f. Dilute Sodium Bicarbonate solution

2. To study the properties of acids and bases (HCl & NaOH) by their reaction with:

 a. Litmus solution (Blue/Red)

 b. Zinc metal

 c. Solid sodium carbonate

3. To perform and observe the following reactions and classify them into:

 i. Combination reaction

 ii. Decomposition reaction

 iii. Displacement reaction

 iv. Double displacement reaction

o 1) Action of water on quick lime

o 2) Action of heat on ferrous sulphate crystals

o 3) Iron nails kept in copper sulphate solution

o 4) Reaction between sodium sulphate and barium chloride solutions

4. i) To observe the action of Zn, Fe, Cu and Al metals on the following salt solutions:

 a. ZnSO₄ (aq)

 b. FeSO₄ (aq)

 c. CuSO₄ (aq)

 d. Al₂(SO₄)₃ (aq)

ii) Arrange Zn, Fe, Cu and Al (metals) in the decreasing order of reactivity based on the above result.

5. To study the dependence of potential difference (V) across a resistor on the current (I) passing through it and determine its resistance. Also plot a graph between V and I.

6. To determine the equivalent resistance of two resistors when connected in series.

7 To determine the equivalent resistance of two resistors when connected in parallel.

8 To prepare a temporary mount of a leaf peel to show stomata.

9 To show experimentally that light is necessary for photosynthesis.

10 To show experimentally that carbon dioxide is given out during respiration.