Madhyamik physical science Question Paper 2019 Solve

WB Madhyamik physical science Solve

Madhyamik Pariksha 2019 Solve- physical science

SUBJECT: physical science Year: 2019

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Group A

1. Which among the following gases absorb long wavelength infrared radiation emitted from the earth’s surface?
  
  (a) N₂ (b) O₂ (c) CH₄ (d) He
  
  Ans. (c) CH₄
  
  1.2 STP 2.24: (At STP, 2.24 L is occupied by)
  
  (a) (4.4g CO₂)
  
  (b) (0.64 g SO₂)
  
  (c) (28g CO)
  
  (d) (16 g O₂)
  
  [C=12, 0=16, S=32]
  
  Ans. (a) 4.4 CO₂
  
  1.3 1 How many molecules of CO₂ will be produced when 1 mole C reacts completely with 1 mole O₂?
  
  (a) 6.022×10²³
  
  (b) 1.806×10²⁴
  
  (c) 6.022×10²²
  
  (d) 6.022×10²⁴
  
  Ans. (a) 6.022×10²³
  
  1.4 For a solid, how many types of thermal expansion coefficients are there?
  
  (a) one (b) two (c) three (d) four
  
  Ans. (c) three
  
  1.5 Which one of the following has the highest wavelength? )
  
  (a) x-ray (b) y-ray (c) infrared ray (d) ultraviolet ray
  
  Ans. (c) infrared ray
  
  1.6 In I the n case of refraction, if the angle of incidence and the angle of refraction are 45° and 30° respectively, then the angle of deviation is
  
  (a) 75° (b) 15° (c) 7.5° (d) 37.59°
  
  Ans. (b) 15°
  
  1.7 Temperature remaining unchanged if the potential difference between the two ends of a conductor is V and the current through the conductor is I, which of the following is true?
  
  (a) V ∝ I (b) V ∝ I² (c) V ∝ I^–² (d) V ∝ I^–²
  
  Ans.(a) V ∝ l
  
  1.8 The relation among electromotive force (V), work (, W), and charge (Q) are.
  
  (a) Q = WV (b) Q= v/W (c) Q =v/W² (d)Q=w/v
  
  Ans. (d) Q=W/v
  
  1.9 For the atom produced by (B-particle emission from a radioactive atom)
  
  (a) mass number increases
  
  (b) atomic number increases
  
  (c) mass number decreases
  
  (d) atomic number decreases
  
  Ans. (b) atomic number increases
  
  1.10 To which group of the long periodic table does the halogen elements belong?
  
  (a) group 1 (b) group 16 (c) group 17 (d) group 2
  
  Ans. (c) group 17
  
  1.11 Solid state of which of the following compounds is composed of ions?
  
  (a) sodium chloride
  
  (b) hydrogen chloride
  
  (c) naphthalene
  
  (d) glucose
  
  Ans. (a) sodium chloride
  
  1.12 Which of the following has the highest ability to conduct electricity?
  
  (a) pure water
  
  (b) an aqueous solution of sugar
  
  (c) liquid hydrogen chloride
  
  (d) an aqueous solution of acetic acid
  
  Ans. (d) aqueous solution of acetic acid
  
  1.13 In the first step of fixation of nitrogen which of the following compounds is formed as a result of lightning
  
  (a) NO (b) NO₂ (c) N₂O₅ (d) HNO₃
  
  Ans. (a) NO
  
  1.14 Which of the following is the formula of bauxite, ore of aluminium ?
  
  (a) A1₂O₃ (b) A1₂O₃H₂O (c) A1₂O₃2H₂O (d) AIF₃.3Nar
  
  Ans. (c) A1₂O₃2H₂O
  
  1.15 Which of the following is the alkyl group containing two carbon atoms?
  
  (a) methyl (b) ethyl (c) propyl (d) isopropyl
  
  Ans. (b) ethyl

Group ‘B’

Answer the following questions (Alternatives are to be noted)

2.1 Write down the unit of calorific value of fuel?

Ans. kilojoule / kg (kj (kg) or Kilo Jute / gm.

OR,

Does the temperature. increase or decrease with an increase in altitude in the stratosphere?

Ans. With the increase in height in the stratosphere, the temperature increases.

2.2 Which radiation, coming from the sun, is prevented by the ozone layer from falling on the earth’s surface?

-Ans. Ultra Violet Rays

2.3 State whether the following statement is true or false:

The volume of gas molecules is taken into consideration in Avogadro’s law.

Ans. False

2.4 The product of volume and pressure of how many grams of N₂ gas is the 224-liter atmosphere at STP? [N = 14]

Ans. S.T. The molecular mass of nitrogen (N₂) at P is = 14 x 2 = 28 grams and the molecular volume in grams is 22.4 liters. pressure = 1 atmosphere

S.T.P. But 22.4 liters of volume is 28 grams of N₂

224 liters volume will be: – x 224 = 280 grams 22.4 So product of volume and pressure = 224 liters x 1 atmospheric pressure

= 224 liters of atmosphere

Ans. 280 grams N₂

2.5 State whether the following statement is true or false:

The constituent particles of a material change position during the conduction of heat through it.

Ans. False

Or,

The width and the cross-section of a conductor remain unchanged, what is the relation between the thermal resistance and thermal conductivity of that conductor?

Ans. The thermal resistance and thermal conductivity of a conductor are inversely proportional to each other.

That is, K = 1/r where K is the thermal conductivity and R is the thermal resistance.

2.6 What will be the angle of incidence when a ray of light passes through the center of curvature of a concave mirror?

Ans. The angle of incidence will be zero degrees.

2.7 How many rectangular surfaces are there in a prism?

Ans. A prism has three rectangular surfaces.

2.8 Give an example of a semiconductor.

Ans. Silicon (Si), Germanium (Ge)

2.9 thin and thick wires of the same conducting material have the same length. Which one of them will carry more current when connected to the same potential difference?

Ans. More current will flow through thicker wire.

2.10 Mention one misuse of the nuclear fission reaction

Ans. The atomic bomb is the gift of nuclear fission but nowadays it is being misused.

OR, which law explains the release of huge amounts of energy in nuclear fusion?

Ans. Energy is emitted according to Einstein’s law E = mc².

2.11 Match the right column with the left column

Left column)

Right column)

2.11.1 Oxide layer protects from attack by water vapor

2.11.2 Group 1 element of the long periodic table having the least reducing property

2.11.3 When the metal remains exposed to air, the metal slowly develops green patches on its surface.

2.11.4 Group 2 element of the long periodic table having the least atomic

radius.

(a)Cu

(b) Be

(d) Li

Ans. 2.11.1 -(c), 2.11.2 (d), 2.11.3-(a), 2.11.4-(b)

2.12 Draw the Lewis dot structure of N₂ molecule, (atomic number of N is 7

Ans.; N + N; ; N N; N N or N₂

2.13 Which kind of electricity is used in electrolysis?)

Ans. D.C.

OR,

Write down the cathode reaction in the electrolysis of acidulated water using platinum electrodes.)

Ans. Action taking place at cathe thode:-

H⁺ + e = H; H + H = H₂

2.14 In electroplating gold on brass [what is the electrolyte used?

Ans. Potassium aero cyanide K [ Au (CN)₂]

2.15 What color is formed in the reaction of ammonia with Nessler’s reagent?

Ans. Brown)

2.16 Write down the formula of the precipitate formed when H₂S gas is passed through an aqueous solution of silver nitrate.

Ans. Silver Sulphide Ag₂S)

OR,

Write the name of the compound which is formed by the reaction of nitrogen with magnesium metal at a high temperature.

Ans. Magnesium Nitride (Mg₃ N₂)

2.17 What is the value of the H–C–H bond angle in methane?

Ans. 109°.5° bond angle

Write the IUPAC name of CH₂ CH₂ COOH

Ans. The IUPAC name of CH₃ CH₂ COOH is Propanoic Acid.

2.18 What is the industrial source of CNG?

Ans. C.N.G. Industrial source of natural gas

Group C

Answer the following questions (Alternatives are to be noted):

3.1 What do you mean by sustainable development?

Ans. Sustainable development is the development that meets the needs of the present generation and also ensures the needs of future generations. Under sustainable development, there is limited use of resources and at the same time, special attention is paid to conservation. So that future generations can be benefited. Apart from this, the process of development is such that it does not disturb the environment and promotes its conservation.

3.2 1g of a gas at 7°C and 2-atmosphere pressure occupies a volume of 410 mL. Determine the molar mass of the gas. (R = 0.082-liter atmosphere mol” 1 K” 1)

Ans.

Or,

A fixed mass of gas occupies a volume of 273 cm’ at STP. At what pressure the above gas will occupy a volume of 300 cm at 27°C?

Ans.

3.3 What is the refractive index of a medium?

Ans. Refractive Index: The ability of a medium to change the direction of a ray of light is called a refractive index. The refractive index of a medium is the ratio of the velocity of light in a vacuum to the velocity of light in that medium.

Ultimate spelling number of water = 4/3

Means = zero here speed of light in air/speed of light in water = 4/3

Or,

Which type of defect of vision is rectified by a convex lens?

Ans. Long-sightedness or Hypermetropia is rectified by a convex lens.

3.4 Two resistances r₁ and r₂ when connected separately to the same potential difference, it was seen that the current flowing through r₁ was six times the current flowing through r₂ Determine the ratio of r and r₂.

3.5 How did Kossel explain the formation of the broadband?

Ans. Explanation of the formation of the ionic bond by Kossel: – According to their theory of Kossel, while making chemical combinations, different atoms exchange electrons located in their outermost orbitals when they come in contact with each other. The exchange of electrons takes place in such a way that both atoms attain a stable conformation like that of the inert gas adjacent to them, that is, the number of electrons in the outer orbit of each atom becomes 8. The electron-releasing atom is positive and the electron-accepting atom is negative. These oppositely charged ions attract each other, as a result of which a stable bond is formed. This bond is called ionic valency.

Or,

Liquid hydrogen chloride cannot conduct electricity, but molten sodium chloride can conduct electricity. Explain.

Ans. Liquid HC/ is a covalent compound that does not dissociate into ions and does not conduct electricity. While NaCl in an aqueous solution or liquid state dissociates into Nat and Cl- ions. Due to which electric current flows. An aqueous solution of NaCl Electrovalent compound.

3.6 Distinguish between sodium chloride and naphthalene by two physical properties.

Ans. Related studies of naphthalene (C₁₀H₈) and rectified (NaCl)

naphthalene (C₁₀H₈)

Sodium chloride (NaCl)

it is a volatile solid

It has very low melting and boiling points

A special type of smell is found in it.

electrolysis in a solid or molten state

There is a bad conductor.

It is a non-volatile solid.

Its melting point and boiling point are high.

It is an odorless substance.

In an aqueous solution or molten state, it is a good conductor of electricity.

3.7 Between two aqueous solutions, one is ferric chloride and the other is aluminum chloride. How would you identify the ferric chloride solution using an aqueous solution of ammonia? Answer with a balanced chemical equation.

Ans. Identification of aqueous solution of ferric chloride: – Aqueous solution of ammonia i.e. (NH₃ + H₂O NH₄OH) is added alternately to an aqueous solution of ferric chloride and an aqueous solution of aluminum chloride. On adding NH₄OH to the ferric chloride solution, a dark-colored precipitate of ferric hydroxide is obtained. But on reacting with aluminum chloride a white-colored precipitate of Al (OH)₃ is obtained.

FeC1₃ +3NH₄OH=Fe (OH)₃ ↓ + 3NH₄CI, AICI₃ + 3NH₄OH-

brown

3NH₄CI+Al (OH)₃ ↓

White

3.8 Why can zinc blend be called both mineral and ore of zinc?

Ans. Zinc blende (ZnS) ore can be used to extract zinc (Zn) in large quantities easily and at a low cost. Hence zinc blende (ZnS) is called both the mineral and the ore of zinc.

Or,

Mention two ways of preventing rusting of iron.

Ans. Protection from rust in iron: – (i) Coating of paint, bitumen, or varnish on the iron rod does not cause rust.

(ii) There is no rust even by doing Galvanization and Tin-plating.

3.9 Write with a balanced chemical equation what happens when methane is burnt in oxygen.

Ans. Burning of Methane: Methane gas is an inflammable gas. Methane gas in the air burns with a blue flame and considerable heat is generated. CO₂ and H₂O are formed in this reaction. The burning of one mole of methane produces 213 kilocalories of heat.

CH₄ +2O₂ → CO₂ +2H₂O +213 K. Cal/mole

Or,

Mention one use of acetic acid and ethyl alcohol.

Ans. Uses of Acetic Acid: Dilute acetic acid is used in the form of vinegar. Uses of Ethyl Alcohol or Ethanol (C₂H₅OH):- Ethyl alcohol is used in the preparation of all types of alcohols.

Group D

4. Answer the following questions (Alternatives are to be noted):

4.1 What is meant by the molar volume of a gas? Mention two reasons for the deviation of real gases from the behavior of ideal gases.

4.2 How many grams of Al is required to prepare 558 g of Fe by the reduction of Fe₂O₃ with Al at high temperature? How many moles of Fe₂O₃ will be required in the reaction?

Fe = 55.8, Al = 27, 0=16]

By heating 32.1g ammonium chloride with calcium hydroxide 10.2 g NH₃, 33.3 g CaCl₂, and 10.8 g H₂O are obtained. How many grams of calcium hydroxide take part in the reaction? How many moles of NH₃, and how many liters of NH₃ at STP are formed in the reaction? (N=14, H= 1)

4.3 Which quantities remain fixed in the definition of the volume expansion coefficient of a gas? Name a non-metal which is a good conductor of heat.

or,

What is meant by ‘the linear expansion coefficient of copper is 17×10^–⁶/°C? Why does the value remain the same even on the kelvin scale?

4.4 What type of mirror is used by dentists? Why a ray of light does not deviate as a result of refraction through a glass slab?

4.5 When an object is placed 20 cm away from a convex lens, no image is obtained on either side of the lens. What is the focal length of the lens? If the refractive index of glass concerning air is 1.5, what is the refractive index of air concerning glass?

or,

The length of an object is 5 cm. An image of length 10 cm is obtained when it is placed at a distance of 2em in front of a convex lens. What are the linear magnification and image distance?)

4.6 Write in brief the basic principle of hydroelectric power generation.

4.7 A current of IA flows when an electric bulb is connected to 220 V mains. What would be the current when the same bulb is connected to 110 V mains?

or,

Find the ratio of resistances for two bulbs of 220V-60W and 110V-60W.

4.8 Explain why a new element is formed by particle emissions but no new element is formed by y-ray emission from a radioactive element.

4.9 Write down Dobereiner’s law of triads. Arrange CI, Br, I, and F in increasing order of their oxidizing power.

or,

What is the important conclusion of Moseley’s experiment? What is the importance of this conclusion regarding the periodic table?

4.10 Write two differences between the conduction of electricity through a metallic wire and an electrolyte during electrolysis. In the electrolytic refining of copper metal, an impure copper rod is used as which electrode?

4.11 Write the names of the chemicals used and the balanced chemical equation in the industrial production of urea.

4.12 (A) and (B) are two unsaturated hydrocarbons, each containing 2 carbon atoms. In reaction with bromine, (A) adds one molecule of bromine per molecule and (B) adds two molecules of bromine per molecule. Write the structural formula of (A) and (B). Write a balanced chemical equation of the reaction of (B) with bromine.

Write a balanced chemical equation of the reaction of sodium hydroxide with acetic acid. Which one between jute and polyethylene is environment-friendly for packaging and why?