State Avogadro’s law. At a certain fixed temperature and pressure the molar volume (V/n) of the real gases are nearly equal and at STP the limit is 22.4 L mol-1. How Avogadro’s law can be arrived at from this information obtained from the experiment? [1 + 2]
Avogadro’s Law: Avogadro's Law states that, at constant temperature and pressure, equal volumes of gases contain an equal number of molecules.
At a certain fixed temperature and pressure the molar volume (V/n) of the real gases are nearly equal and at STP the limit is 22.4 L mol-1.
Then, V_1\over n_1 = V_2\over n_2
or, V_1\over n_1 = V_2\over n_2 = K, where K is Avogadro constant,
This implies that V ∝ n
As the number of moles increases, the volume increases, supporting Avogadro’s Law.
Question ID: 273
Uploaded on: September 22, 2024
A and B react to produce C according to the following chemical equation 2A + B → C A, B and C are the formulas for three gaseous substances. The vapour densities of A and B are 32 and 16 respectively. Find out the vapour density of C. [3] OR According to the following chemical equation [3] 2ZnS + 3O2 → 2ZnO + 2SO2 From 100 mole of ZnS (Zn = 65.5, S = 32, O = 16).
For A:
Vapour density of A = 32
Molar Mass of A (MA) = 2 × 32 = 64
For B:
Vapour density of B = 16
Molar Mass of A (MA) = 2 × 16 = 32
From the balanced equation:
2A + B → C
The molar mass of C (MC) can be calculated using the molar masses of A and B:
MC = 2MA + MB
= 2 × 64 + 32
= 160
∴ Vapour density of C = 160\\over 2 = 80
OR
(i) According to the equation, 2 moles of ZnS produce 2 moles of ZnO.
So, 100 moles of ZnS will produce 100 moles of ZnO.
Molar mass of ZnO = 65.5 + 16 = 81.5 g
∴ Mass of 100 moles of ZnO = 8150 g
(ii) According to the equation, 2 moles of ZnS produce 2 moles of SO2.
Therefore, 100 moles of ZnS will produce 100 moles of SO2.
Question ID: 274
Uploaded on: September 22, 2024
Give an example of the volume expansion of a liquid on heating. The area of a solid substance at a temperature of T1K is A1 sq m and that at a temperature of T2K is A2 sq m. Write down the mathematical expression for the coefficient of area expansion with unit, of that solid substance. [1+2] OR Write down the three factors on which the conduction of heat through a solid substance depends. [3]
An example of volume expansion of a liquid is water when heated. As the temperature increases, the molecules gain kinetic energy, causing the water to expand and occupy a larger volume.
Coefficient of Area Expansion (β) :
β = ΔA\over A_1 ΔT
Units: K-1 or °C-1
OR
The conduction of heat through a solid depends on:
Question ID: 275
Uploaded on: September 22, 2024
What is the dispersion of light? Will there be a dispersion of white light within a glass slab after refraction when white light is incident on the glass slab at an angle of 45ºC? [2+1]
Dispersion of Light is the process by which white light splits into its constituent colours when it passes through a prism.
No, there will not be a dispersion of white light within a glass slab.
Question ID: 276
Uploaded on: September 22, 2024
The principal section of a prism is an equilateral triangle. If a ray of light is incident at an angle of 30o on one of the refracting surfaces and emerges at an angle of 45o from the other refracting surface, what is the angle of deviation? [3] OR What will be the velocity and wavelength of a light in a medium of refractive index 1.5 if the wavelength of that light is 6000 Å in air medium ? [1+2]
Angle of incidence (i) = 30º
Angle of emergence (e) = 45º
A = 60º (equilateral triangle prism)
Deviation (δ) = i + e -A
= 30º + 45º - 60º
= 15º
The angle of deviation is 15º.
OR
Calculate the Velocity of Light in the Medium
Speed of light in vacuum (c) = 3 × 108 m/s
Refractive index (μ) = 1.5
Velocity of Light in the Medium = 3 × 10^8\over 1.5
= 2 × 108 m/s
Calculate the Wavelength in the Medium
λ0 = wavelength in air (given as 6000 A˚)
λ = λ_o<sup> </sup>\over 1.5 = 6 × 10^{-7} \over 1.5
λ = 4 × 10-7 m = 4000 Å
Question ID: 277
Uploaded on: September 22, 2024
Two metallic conductors A and B of the same lengths have resistivities of 1.6 × 10-8 and 3.2 × 10-8 respectively. These two conductors are separately connected to the same potential difference. What should be the ratio of their cross sections in order to have the same current flowing through each of them? OR The series combination of two 10 ohm resistances is connected in parallel combination with a 20-ohm resistance. Determine the equivalent resistance of the final combination.
ρA = 1.6×10-8 Ω⋅m
ρB = 3.2×10-8 Ω⋅m
R =ρL\over A
A_A\over A_B = ρ_A\over ρ_B
Or, A_A\over A_B = 1.6×10^{-8}\over 3.2×10^{-8} = 1.6\over 3.2
Or, A_A\over A_B = 1\over 2
The ratio of their cross sections should be = 1 : 2
OR
Calculate the Series Combination
Rs = R1 + R2
Rs = 10 Ω + 10 Ω = 20 Ω
Calculate the Parallel Combination
{1\over R_{eq}} = {1\over R_s} + {1\over R_3}
or, {1\over R_{eq}} = {1\over 20} + {1\over 20}
or, {1\over R_{eq}} = {1 + 1\over 20}
or, {1\over R_{eq}} = {2\over 20}
or, Req = 10 Ω
Question ID: 278
Uploaded on: September 22, 2024
What is meant by electrical power? The rating of a bulb is written as 220 V - 100 W - What is its meaning? [1+2]
Electrical power is the rate at which electrical energy is consumed or converted into other forms of energy.
The rating of a bulb as 220 V - 100 W means:
Question ID: 279
Uploaded on: September 22, 2024
From which part of the atom are the radioactive rays emitted? Which of the radioactive rays has the highest penetrating power and which has the highest ionising power? [1+2]
Radioactive rays are emitted from the nucleus of an atom.
Penetrating Power and Ionizing Power
Question ID: 280
Uploaded on: September 22, 2024
Mention the dissimilarity of properties of hydrogen with one property of group 1 elements and two properties of group 17 elements. [1+2] OR Arrange as directed : a) Na (11), K (19), Li (3), Rb (37) belonging to Group 1 of the long periodic table according to decreasing order of atomic radius. b) S(16), O (8), Te (52), Se (34) belonging to Group 16 of the long periodic table according to increasing order of electronegativity. c) Ca (20), Be (4), Sr (38), Mg (12) belonging to Group 2 of the long periodic table according to decreasing order of reducing power. (The atomic numbers have been given within the first brackets after the symbols of the elements [1+1+1]
Dissimilarity with Group 1 Elements:
Dissimilarity with Group 17 Elements:
OR
Decreasing Order of Atomic Radius:
Rb > K > Na > Li
Increasing Order of Electronegativity (Group 16):
Te < Se < S < O
Decreasing Order of Reducing Power (Group 2):
Ca > Sr > Mg > Be
Question ID: 281
Uploaded on: September 22, 2024
On what basis electrolytes have been classified as strong and weak electrolytes? Give an example of a strong electrolyte. [2+1]
Electrolytes are classified as strong and weak based on their ability to dissociate into ions when dissolved in water.
Strong Electrolytes: These completely dissociate into ions in solution, resulting in a high concentration of ions. This leads to good electrical conductivity.
Weak Electrolytes: These partially dissociate into ions in solution, resulting in a lower concentration of ions and therefore weaker electrical conductivity.
Question ID: 282
Uploaded on: September 22, 2024
Write mentioning the name of the catalyst and condition, how nitric oxide is manufactured by oxidising ammonia with the help of aerial oxygen. Write also the balanced chemical equation of the reaction. [2+1]
Manufacturing of Nitric Oxide
Balanced Chemical Equation
4NH3 (g) + 5O2 (g) {{\overset{Pt,\ 800°C, 5 - 7 atm}{\longrightarrow}}} 4NO(g) + 6H2 O(g)
Question ID: 283
Uploaded on: September 22, 2024
Two different organic compounds A and B have the same molecular formula of C2H6O. A reacts with metallic sodium to produce hydrogen gas but B does not react with metallic sodium. Write structural formulas of the compounds A and B. Write the balanced chemical equation of the reaction of A with metallic sodium. [2+1] OR Write the condition for the reaction of the addition of hydrogen to ethylene. Write the balanced chemical equation of the reaction. Mention one use of CNG. [2+1]
Compounds A and B with the molecular formula C2H6O could be:
Compound A
Compound B
Reaction of A (Ethanol) with Metallic Sodium
2CH3CH2OH + 2Na → 2CH3CH2ONa + H2(g)
OR
Catalyst Required: Nickel (Ni)
Temperature: 160°C
Balanced Chemical Equation
Ethylene (C2H4) reacts with hydrogen (H2) to form ethane (C2H6).
C2H4 (g) + H2 (g) {{\overset{Ni,\ 160 °C}{\longrightarrow}}} C2H6 (g)
Compressed Natural Gas (CNG) is commonly used as a fuel for vehicles.
Question ID: 284
Uploaded on: September 22, 2024