Odisha B.Ed Entrance Physical Science Solutions 2023 Download

Solution : The correct answer is: (B) 2nd law

The second law of motion, also known as Newton’s second law, states that the force acting on an object is directly proportional to the rate of change of its momentum. Mathematically, it is expressed as:

Where:

is the force applied to the object,

is the mass of the object,

is the acceleration produced in the object.

This equation quantitatively defines how force, mass, and acceleration are related. Therefore, the quantitative definition of force is obtained from Newton’s 2nd law.

Solution : The correct answer is: 10 J

The work done during the process of bringing a moving body to rest is equal to the change in its kinetic energy. The kinetic energy () of an object with mass and velocity is given by:

Initially, the body has a kinetic energy of:

When the body comes to rest, its final kinetic energy () is zero.

Therefore, the work done () is the change in kinetic energy:

However, work is a scalar quantity, and its magnitude is taken as positive. So, the magnitude of work done is:

Thus, the work done during the process is 10 J.

Solution : The correct answer is: Bernoulli’s law

A Venturi meter is a device used to measure the flow rate of a fluid in a pipe. It operates based on Bernoulli’s principle, which states that as the velocity of a fluid increases, the pressure exerted by the fluid decreases, and vice versa, assuming the fluid’s flow is steady and the fluid is incompressible.

In a Venturi meter, a constriction is created in a pipe, causing the fluid to accelerate as it passes through the narrow section (Venturi throat). According to Bernoulli’s principle, the increase in fluid velocity in the narrow section results in a decrease in pressure. This pressure difference is used to measure the flow rate of the fluid.

Therefore, a Venturi meter works on the principle of Bernoulli’s law.

Solution: The correct answer is: (A) From mechanical to electrical

In a dynamo, mechanical energy is transformed into electrical energy. A dynamo is a device that converts mechanical energy, often derived from motion or rotation, into electrical energy through electromagnetic induction.

When a conductor (such as a coil of wire) is rotated within a magnetic field, a change in magnetic flux occurs, inducing an electromotive force (EMF) or voltage across the conductor. This induced voltage leads to the flow of electric current, resulting in the conversion of mechanical energy into electrical energy.

Solution: The correct answer is: (C) Metallic Conductor

Ohm’s law states that the current () passing through a conductor is directly proportional to the voltage () across its terminals, provided the temperature and other physical conditions remain constant. Mathematically, Ohm’s law is represented as:

Where:

is the voltage,

is the current,

is the resistance of the conductor.

This law is applicable to metallic conductors, which are materials that follow a linear relationship between voltage and current and have a constant resistance within a specific temperature range.

Solution: The correct answer is: (B) 30 J

The energy gained by a charged object when it is moved through a potential difference () is given by the formula:

Where:

is the energy gained,

is the charge,

is the potential difference.

Given that the mass () of the body is 2 kg and the charge () is 5 C, and the potential difference () is 6 V:

Therefore, the energy gained by the body is 30 J.

Solution: The correct answer is: (D) Energy

Lenz’s law of electromagnetic induction states that the direction of the induced electromotive force (emf) in a closed circuit is such that it opposes the change in magnetic flux that caused it. This law is a consequence of the conservation of energy.

When there is a change in magnetic flux through a circuit, an emf is induced, which leads to the flow of current. This induced current creates its own magnetic field, which opposes the change in the original magnetic field. The work done in establishing this opposing current comes at the expense of the external energy causing the change in magnetic flux.

By opposing the change in magnetic flux, Lenz’s law ensures that the total energy in the system remains conserved. This principle is in line with the conservation of energy, which states that energy cannot be created or destroyed, only transferred or transformed.

Solution: The correct answer is: (B) 300 m/s

The velocity of sound in air depends on factors like temperature, pressure, and humidity. However, at Standard Temperature and Pressure (STP), which is typically taken as 0 degrees Celsius and 1 atmosphere pressure, the approximate velocity of sound in dry air is about 331.5 meters per second (m/s).

As the temperature of the medium increases, the speed of sound also increases. For example, in air, the speed of sound is 331 m/s at 0 ºC and 344 m/s at 22 ºC. This temperature dependence explains why the speed of sound in air at standard temperature and pressure (STP) is approximately 300 m/s. While this value might seem lower than the actual speed at higher temperatures, the context provided indicates that the answer should be the nearest value, and in this case, 300 m/s is indeed the nearest value to the accurate speed of sound at STP.

So, the velocity of sound in air at STP is approximately 300 m/s.

Solution : The correct answer is (B) Halved.

In Young’s double slit experiment, when a coherent light source passes through two closely spaced slits, it creates an interference pattern of bright and dark fringes on a screen. The fringe width () is the distance between two consecutive bright or dark fringes.

The fringe width is given by the formula:

Where:

is the wavelength of the light,

is the distance between the double slits and the screen,

is the separation between the slits.

When the separation between the slits is doubled while staying within the wavelength range of the light used, the fringe width decreases, which means that the fringe separation becomes smaller. This phenomenon occurs because the fringe width is inversely proportional to the separation between the slits. Therefore, if the separation is doubled, the fringe width will be halved.

Solution: The correct answer is: (D) Sixteen times the original value

The radiant emittance of a black body is a measure of the amount of energy it radiates per unit area per unit time. It is also known as the black body radiation or the power emitted per unit area.

According to Stefan-Boltzmann law, the radiant emittance () of a black body is directly proportional to the fourth power of its absolute temperature (). Mathematically, the law is given by:

Where:

is the Stefan-Boltzmann constant.

If the temperature () is doubled, the radiant emittance () will become:

Comparing the new radiant emittance () to the original value (), we can see that is sixteen times the original value ():

So, when the temperature of a black body is doubled, its radiant emittance becomes sixteen times the original value.

Solution : The correct answer is: (B) 12, 14, 12

In an atom, the atomic number (proton number) determines the element’s identity. Since the atom is magnesium (Mg) with atomic number 12, it has 12 protons.

The mass number of the isotope is the sum of protons and neutrons. Given that the mass number is 26, and the number of protons is 12, subtracting protons from the mass number gives us the number of neutrons: 26 – 12 = 14 neutrons.

Since atoms are electrically neutral, the number of electrons is equal to the number of protons. Therefore, the number of electrons is also 12.

Solution : The correct answer is the first option: CO, CN‾, NO⁺, C₂^2-.

Iso-electronic species are atoms, ions, or molecules that have the same number of electrons, regardless of the elements they belong to. In this case:

• CO (Carbon Monoxide) has 10 electrons.
• CN‾ (Cyanide ion) has 10 electrons.
• NO⁺ (Nitrosonium ion) has 10 electrons.
• C₂^2- (Dicyanide ion) has 10 electrons.

Each of these species has 10 electrons, making them iso-electronic with each other.

The other options do not consist of iso-electronic species as they do not have the same number of electrons.

Solution : Grace Mark The correct answer is: 1σ, 2π.

The option (D) 1σ, 2π is not present in the Question Paper. So, it will be count as Grace Mark.

CaC₂ refers to calcium carbide. The structure of calcium carbide is CaC≡C. In this molecule:

• There is 1 sigma (σ) bond: The sigma bond is between calcium (Ca) and the carbon (C) atom on the left.
• There are 2 pi (π) bonds: The two pi bonds are formed between the carbon (C) atoms due to the triple bond (≡).

Therefore, the molecule CaC₂ has 1 sigma (σ) bond and 2 pi (π) bonds.

Solution : The correct answer is: (D) Fe²⁺

Fe²⁺ has the maximum number of unpaired electrons among the given options.

Fe²⁺ has the electronic configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶. In this configuration, there are 4 unpaired electrons in the 3d orbitals, which is the maximum among the provided ions.

Mg²⁺ has 0 unpaired electrons as its electronic configuration is 1s² 2s² 2p⁶.

Ti³⁺ has 1 unpaired electron as its electronic configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d².

V³⁺ has 3 unpaired electrons as its electronic configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d².

Solution : The correct answer is: (A) CO

A neutral oxide is one that does not show acidic or basic properties when dissolved in water. Among the given options, (A) CO (Carbon Monoxide) is neutral since it does not significantly dissociate into ions when dissolved in water, making it neither acidic nor basic.

CO (Carbon monoxide) is a neutral oxide among the given options.

Carbon monoxide (CO) is a molecular compound that contains one carbon atom and one oxygen atom. It has a neutral charge and does not exhibit acidic or basic properties.

SnO₂ (Tin dioxide), ZnO (Zinc oxide), and SiO₂ (Silicon dioxide) are oxides that are not neutral. SnO₂ and SiO₂ are acidic oxides, while ZnO is a basic oxide.

Solution : The oxidation number of nitrogen in the structure N=N-N-H is -2. In this structure, the nitrogen atom bonded to the hydrogen atom has an oxidation state of -2. The other nitrogen atoms are involved in double and single bonds, but their oxidation states remain unchanged in this context.

Solution : The correct answer is: (D) –3

In the molecule N₃H, the nitrogen atom attached to the single hydrogen atom is in the –3 oxidation state.

In the given representation N=N-N-H, the central nitrogen atom is connected to two other nitrogen atoms by double bonds (N=N) and to a hydrogen atom (H). Since each single bond contributes a –1 oxidation state to the attached atom, and nitrogen prefers to have a –3 oxidation state in this context, the central nitrogen atom has an oxidation state of –3.

Options (A) 0, (B) +3, and (C) –2 are not correct oxidation states for the central nitrogen atom in this compound.

Solution : The balanced chemical equation for the given reaction is:

In the balanced equation, the coefficients indicate the stoichiometric coefficients of each reactant and product. The balanced coefficients for a, b, c, and d are 1, 5, 4, and 5 respectively, making option (D) the correct answer.

Solution : The correct answer is (B) 6, 5, 8, 5.

Given equation:

2MNO₄^‾ + aH⁺ + bH₂O₂ → 2Mn²⁺ + cH₂O + dO₂

To balance the equation, let’s break down the equation into individual atoms and ions:

• 2 Mn atoms on the right side require Mn atoms on the left side, so (since 2 * 3 = 6).
• 2 N atoms on the left side require H atoms on the right side. Since , 6 H atoms are added on the right side.
• 4 O atoms on the left side require H atoms on the right side (from H₂O₂), so .
• 5 O atoms on the left side require O atoms on the right side, so .
• Remaining H atoms on the left side are contributed by H₂O₂ molecules. Since and , (since H atoms are contributed by each H₂O₂).

Therefore, the balanced equation becomes:

2MNO₄^‾ + 6H⁺ + 5H₂O₂ → 2Mn²⁺ + 8H₂O + 5O₂

Solution : The correct answer is (C) Tetrathionate ion.

The reduction of thiosulfate (S₂O₃^2-) with iodine (I₂) gives tetrathionate ion (S₄O₆^2-).

The balanced chemical equation for the reaction is:

S₂O₃^2- + I₂ + 3H₂O → S₄O₆^2- + 2I^– + 6H⁺

In this reaction:

• Thiosulfate ion (S₂O₃^2-) is reduced to tetrathionate ion (S₄O₆^2-).
• Iodine (I₂) is reduced to iodide ion (I^–).

The other options do not represent the correct product formed in the reduction of thiosulfate with iodine.

Solution : The correct answer is (C) Starch.

The indicator used in iodometric titration is starch.

In iodometric titration, starch is used as an indicator to detect the endpoint of the titration. Starch forms a blue-black complex with iodine, indicating the presence of excess iodine in the reaction mixture.

During the titration, iodine reacts with the substance being titrated. When the reaction nears completion, the solution’s color changes from yellowish-brown to a pale yellow. Adding a small amount of starch solution turns the solution blue-black due to the formation of the starch-iodine complex, signaling the endpoint of the titration.

The other options are indicators used in different types of titrations, but not in iodometric titrations.

Solution : The correct answer is (C) 3.

The balanced half-reaction equation is:

NO₃^‾ + 4H⁺ + e → 2H₂O + NO

In this equation:

• NO₃^‾ gains 3 oxygen atoms to form 2H₂O.
• The oxidation state of nitrogen in NO₃^‾ changes from +5 to +2 in NO, gaining 3 electrons.
• Hydrogen ions (H⁺) gain 2 electrons to form 2H₂O.

So, in total, 3 electrons are involved in the half-reaction.

The other options do not correctly represent the number of electrons involved in the balanced half-reaction.