State Lenz’s law related to electromagnetic induction.
Lenz law states that the direction of the induced e.m.f. is such as to oppose the cause of induction or the cause which produces.
Question ID: 140
Uploaded on: September 15, 2024
Write with an example of how according to Lewis’s concept a covalent bond is formed. OR Why the bond in sodium chloride can’t be expressed as Na-Cl?
According to Lewis’s concept, a covalent bond is formed when two atoms share a pair of electrons. For example, in a hydrogen molecule (H₂), each hydrogen atom shares its single electron with the other, forming a single covalent bond:
H⋅ + ⋅H → H − H
OR
The bond in sodium chloride (NaCl) cannot be expressed as Na-Cl because NaCl is an ionic compound, not a covalent one. Sodium (Na) donates an electron to chlorine (Cl), forming Na⁺ and Cl⁻ ions, which are held together by electrostatic forces rather than sharing electrons.
Question ID: 141
Uploaded on: September 15, 2024
Give one example each of a liquid and a solid covalent compound.
Question ID: 142
Uploaded on: September 15, 2024
Write with a balanced chemical equation what happens when H2S gas is passed through an aqueous copper sulphate solution.
When H2S gas is passed through an aqueous copper sulfate (CuSO4) solution, it reacts to form copper sulfide (CuS) and sulfuric acid (H2SO4). Balanced chemical equation:
CuSO4(aq) + H2S(g) → CuS(s) + H2SO4 (aq)
Question ID: 143
Uploaded on: September 15, 2024
Write down the cathode reaction when an aqueous solution of MSO4 (M=metal) is electrolysed. Write with reason whether the reaction is oxidation or reduction. OR Give one use of each copper and aluminium.
When an aqueous solution of MSO4 (where M is a metal) is electrolyzed, the cathode reaction is:
M2+(aq) + 2e− → M (s)
Reason: This reaction is reduction because the metal cations (M2+) gain electrons (reduced) to form solid metal (M) at the cathode.
OR
Use of Copper:
Use of Aluminium:
Question ID: 144
Uploaded on: September 15, 2024
What is the condition of the substitution reaction of methane with chloride? Write the balanced chemical equation of the first step of the reaction. OR Write with a balanced chemical equation what happens when ethanol reacts with metallic sodium.
In the substitution reaction of methane with chlorine, the condition required is exposure to ultraviolet (UV) light or high temperatures. This initiates the reaction by generating chlorine radicals.
The balanced chemical equation for the first step (chlorination) is: CH4 + Cl2 \overset \text{U V light} {\longrightarrow} CH3Cl + HCl
OR
The balanced chemical equation for the reaction of ethanol with metallic sodium is:
2C2H5OH + 2Na → 2C2H5ONa + H2
In this reaction, ethanol (C2H5OH) reacts with sodium (Na) to form sodium ethoxide (C2H5ONa) and hydrogen gas (H2).
Question ID: 145
Uploaded on: September 15, 2024
Establish an ideal gas equation on the basis of Boyle’s law, Charles’ law and Avogadro’s law.
The state of any gas can be completely be described by four variables such as pressure (P), Volume (V), Absolute temperature (T) and number of moles (n) of the gas.According to Boyle’s law:
V ∝ 1/P (T and n are constant)
According to Charle’s law:
V ∝ T (P and n are constant)
According to Avogadro’s law:
V ∝ n (P and T are constant)
By method of compound variation: V ∝ nT/p,
When P, T and n of the gas vary
Therefore, V ∝ RnT/P (R = molar gas constant).
Or, PV = nRT. This equation is called the Ideal Gas Equation.
Question ID: 146
Uploaded on: September 15, 2024
SO2 required for the industrial production of sulphuric acid is produced by burning iron pyrites in excess air current. The chemical equation of the reaction is given below: 4FeS2 + 11O2 → 2Fe2O3 + 8SO2 How many grams of FeS2 is required for the production of 512 grams of SO2? (Fe=56, S=32, O=16) OR By heating 200 grams of a metal carbonate 112 grams of metal oxide and a gaseous compound are processed. The vapour density of the gaseous compound is 22. How many molecules of the gaseous compound are processed in the reaction?
Balanced Chemical Eq
4FeS2 + 11O2 → 2Fe2O3 + 8SO2
480 g 512 g
From the equation, it is evident that 480 g of FeS2 is required to produce 512 g of SO2
OR
According to the law of conservation of mass, the mass of the gaseous compound produced = 200 - 112 = 88 g
Molecular weight (M) = 2 × VD
= 2 × 22
= 44 g
Number of moles (n) = 88/44 = 2
Question ID: 147
Uploaded on: September 15, 2024
What is thermal conductivity? What is its SI unit? OR Define the coefficient of surface expansion. Write its SI unit.
The thermal conductivity of a material is the amount of heat which when passes normally in one second through the opposite faces of unit cube (i.e, 1 m cube), the difference in temperature between its 2 opposite faces is 10C. The S.I. unit of thermal conductivity is J.m-1.K-1.s-1.
OR
The coefficient of linear expansion of a substance is the change in length relative to its original length at 0ºC per unit of temperature.
The S.I. unit of the coefficient of linear expansion of a substance is K-1.
Question ID: 148
Uploaded on: September 15, 2024
How can an erect and magnified image be formed with the help of a convex lens? With the help of which type of lens long-sightedness can be rectified?
When the object is placed between focus and the optical centre, an erect and magnified image be formed with the help of a convex lens. Long Sightedness is rectified using a convex lens.
Question ID: 149
Uploaded on: September 15, 2024
If the velocity of light in a medium is 2×108 m/s, what will be the refractive index of that medium? OR The refractive index of a medium with respect to air is √2. If the angle of incidence of a ray of light in air is 45° determine the angle of deviation for that ray in case of refraction.
The R.I of a medium is given by,
μ = Velocity of light in vacuum/Velocity of light in the medium
or, μ = 3 × 10^8\over 2 × 10^8
or, μ = 3\over2 = 1.5
OR
Refractive Index (μ) = sin\ i\over sin\ r
√2 = sin\ 45º\over sin\ r
sin r = sin\ 45º\over √2
sin r = {1\over √2}\over √2
sin r = 1\over 2 = sin 30º
∠ r = 30º
Since refraction is taking place from rarer to denser medium,
angle of deviation,
δ = ∠ i - ∠ r = 450 - 300 = 150.
Question ID: 150
Uploaded on: September 15, 2024
Write Joule’s law related to the heating effect of current.
Joule’s law of heating :
If H amount of heat is produced in a conductor of resistance R, when a steady current I is passed through it for time t, then H is
Therefore, H = kI2Rt (k = Joule's constant)
Question ID: 151
Uploaded on: September 15, 2024