Write one characteristic of each of electrical heater wire and fuse wire.
Electrical Heater Wire: Has a high resistance and High Melting Point.
Fuse Wire: Has a low melting point and low resistance.
Question ID: 393
Uploaded on: September 26, 2024
Show by drawing a Lewis dot diagram of CH4 that CH4 is formed by covalent bonds. (Atomic numbers of H and C are 1 and 6 respectively)
Lewis dot diagram of CH4
Question ID: 394
Uploaded on: September 26, 2024
Show by the help of a property of sodium chloride that sodium chloride is composed of ions. OR Show how ionic bond is formed in sodium chloride. (Atomic numbers of Na and CI are 11 and 17 respectively)
Sodium chloride (NaCl) conducts electricity when dissolved in water, indicating it is composed of ions. Upon dissolution, NaCl dissociates into sodium ions (Na⁺) and chloride ions (Cl⁻), which are free to move in the solution, allowing it to conduct electric current. This behaviour confirms its ionic nature.
OR
Sodium chloride (NaCl) is formed through the transfer of an electron from sodium to chlorine, resulting in the formation of Na⁺ and Cl⁻ ions, which are held together by ionic bonds.
Question ID: 395
Uploaded on: September 26, 2024
Write, with the balanced chemical equation, what happens when H2S gas is passed through an aqueous solution of Pb(NO3)2.
When hydrogen sulfide (H2S) gas is passed through an aqueous solution of lead(II) nitrate (Pb(NO3)2), a chemical reaction occurs that results in the formation of lead(II) sulfide (PbS) as a precipitate and nitric acid (HNO3) as a byproduct.
Balanced Chemical Equation:
H2S(g) + Pb(NO3)2 (aq) → PbS(s) ↓ + 2HNO3 (aq)
Question ID: 396
Uploaded on: September 26, 2024
In the extraction of metal by the process of electrolysis at which electrode does the following reaction occur ? M+ + e− ⇌ M (M = Metal) Is it an oxidation or a reduction reaction? Answer with reason. OR Mention one use of aluminium. Why acidic foods should not be kept in an aluminium container?
The reaction occurs at the cathode during the process of electrolysis.
This is a reduction reaction because it involves the gain of electrons.
OR
One use of aluminium is in packaging materials, such as aluminium foil.
Acidic foods should not be kept in an aluminium container because they can react with the metal, leading to the leaching of metal into the food, which alters the taste and poses health risks due to potential neurotoxicity from high aluminium intake.
Question ID: 397
Uploaded on: September 26, 2024
How is polyethene produced by the polymerisation reaction of ethylene? OR How can the following conversion be carried out? HC = CH → CH3CH3
Polymerisation of ethylene: Ethylene is liquified at high pressure (1500-2000 atm). In the presence of catalysts such as peroxide, oxygen or chromium oxide and at temperatures 150℃-200℃, a large number of ethylene molecules join to form a white solid called polyethylene or polythene.
nC2H4→(C2H4)n
OR
The conversion of ethyne (HC≡CH) to ethane (CH₃CH₃) can be carried out through hydrogenation using platinum (Pt) as a catalyst.
HC = CH + H2 {\overset{Pt}{\longrightarrow}} CH3CH3
Question ID: 398
Uploaded on: September 26, 2024
What is an ideal gas? What is the effect of the increase in temperature on the pressure of a gas kept in a closed container? Answer with reason. [1 + 2]
Gases which obey the PV=RT (for 1 mole) equation at all temperature and pressure are called ideal gases.
The pressure of a gas in a closed container increases with an increase in temperature due to the kinetic theory of gases. As temperature rises, gas molecules move faster, leading to more frequent and forceful collisions with the container walls, which raises the pressure.
Question ID: 399
Uploaded on: September 26, 2024
On burning sulfur in oxygen, sulfur dioxide is produced S + O2 → SO2 For producing 2240 L of SO2 at STP (i) How many grams of sulfur and (ii) how many moles of O2 will be required? (0 = 16, S = 32) [3] OR On burning 480 g of a solid compound in 352 g of oxygen, 320 g of another solid compound and a gaseous compound are produced. If the vapour density of the gaseous compound is 32, how many moles of the gaseous compound are formed? [3]
Balanced Chemical Equation:
S + O2 → SO2
32 g 1 mol 22.4 L
(i) Amount of S required to produce 22.4 L of SO2 = 32 g
⇒ Amount of S required to produce 2240 L of SO2 = 32\over 22.4 × 2240 = 3200 g
(ii) The number of moles of oxygen required to produce 22.4 L of SO2 = 1
⇒ The number of moles of oxygen required to produce 2240 L of SO2 = 1\over 22.4 × 2240 = 100 mol
OR
Given Data
Molar Mass = 2 × Vapor Density
= 2 × 32
= 64
Mass of gaseous compound=480 g + 352 g − 320 g
= 512 g
∴ Moles of gaseous compound = 512/64 = 8 mol
Question ID: 400
Uploaded on: September 26, 2024
Define the coefficient of volume expansion of a solid and write its mathematical form. [1 + 2] OR Give one example of each of the thermal expansion of solid, liquid and gaseous substances from everyday experience. [1 + 1 + 1]
Definition: The coefficient of volume expansion of a solid is defined as the fractional increase in its volume per degree rise in temperature.
Coefficient of volume expansion (γ) = V_2 - V_1\over V_1(θ_2-θ_1)
OR
Examples of Thermal Expansion
Question ID: 401
Uploaded on: September 26, 2024
In the case of refraction if the angle of incidence is 45° and the refracted ray makes an angle of 60° with the normal, what will be the value of the angle of deviation? If an object of 6 cm in length is placed at a distance of 2.4 cm in front of a convex lens, the image is formed at a distance of 4.8 cm from the lens. What are linear magnification and the length of the image? [1 + 2] OR The velocity of light in the glass medium is 2 × 105 Kms-1 and the velocity of light in water medium is 2.25 × 105 Kms-1. Determine the ratio of refractive indices of glass and water medium.
Angle of incidence (i) = 45º
Angle of refraction (r) = 60º
Angle of deviation (δ) = i − r
= 45º - 60º = −15º
The negative sign indicates that the deviation is towards the normal.
Given:
Object length (h) = 6 cm
Object distance (u) = - 2.4 cm
Image distance (v) = 4.8 cm
(i) Linear Magnification (m) = 4.8\over -2.4 = -2
(ii) Length of the Image = m × h = - 2 × 6 cm = -12 cm
The negative sign indicates that the image is inverted.
OR
Speed of light in vacuum = 3 × 105 km/s
Speed of light in glass = 2 × 105 Km/s
Speed of light in water = 2.25 × 105 Km/s
μglass = 3 × 10^5\over 2 × 10^5 = 1.5
μwater = 3 × 10^5\over 2.25 × 10^5 = 4/3
Ratio = μglass : μwater = 1.5 : 4/3 = 9:8
Question ID: 402
Uploaded on: September 26, 2024
Write one use of each of the x-ray and ϒ-ray. Mention one harmful effect of γ-ray.
Uses
Harmful Effect of γ-ray
One harmful effect of gamma rays is that they can cause DNA damage in living cells, potentially leading to mutations, cancer, or radiation sickness.
Question ID: 403
Uploaded on: September 26, 2024
Two metallic wires A and B of the same length are made of the same material. The radius of wire A is double the radius of wire B. What is the ratio of resistances of the two wires? [3] OR There are three 220V-60W electric lamps and two 220V-100W electric fans in the house. The electric lamps are lit for 5 hours a day and the fans are run for 10 hours a day. If the cost per B.O.T unit is Rupees 5, what will be the cost of electricity for 30 days?
R = ρ l\over a
or, R = ρ l\over πr^2
⇒ R ∝ 1\over r^2
⇒ R_A\over R_B = ({r_B})^2\over ({r_A})^2
Given: rA = 2rB
⇒ \text{R}_\text{A}\over \text{R}_\text{B} = ({r_B})^2\over ({2r_B})^2
⇒ \text{R}_\text{A}\over \text{R}_\text{B} = ({r_B})^2\over 4({r_B})^2
⇒ \text{R}_\text{A}\over \text{R}_\text{B} = 1\over 4
∴ The ratio of resistances of the two wires 1 : 4.
OR
Energy Consumption of the Lamps
Energy Consumption of the Fans
Total Energy Consumption per Day
= 900Wh + 2000 Wh
= 2900 Wh
= 2.9 kWh
Total Energy Consumption (30 Day) = 2.9 kWh × 30
= 87 kWh
Total cost = ₹ 5 × 87 = ₹ 435
Question ID: 404
Uploaded on: September 26, 2024