Chargement....
|
Appuyez et maintenez pour déplacer |
|||
|
Cliquez ici pour fermer |
|||
Question 1 Rapport
A medium texture soil with high organic matter is
Détails de la réponse
A medium texture soil with high organic matter is best described as loamy soil. Here's why:
Loamy soil is a type of soil that is characterized by a balanced mixture of sand, silt, and clay particles. Because of this blend, loamy soil is not too coarse like sandy soil, nor is it too compact and dense like clay soil, making it a medium texture.
Moreover, loamy soil is renowned for its high organic matter content. This means that it contains a significant amount of decomposed plant and animal residues, which enrich the soil and provide essential nutrients for plant growth. This high organic content enhances the soil's fertility and structure, enabling it to retain moisture yet drain well, making it ideal for farming and gardening.
In conclusion, due to its balanced texture and richness in organic matter, loamy soil is the best fit for a medium-textured soil with high organic matter.
Question 2 Rapport
A light ray passing from air into water at an angle of 30º from the normal in air would
Détails de la réponse
When light passes from one medium to another, such as from air to water, it bends or refracts. This phenomenon is described by Snell's Law, which states: n₁ * sin(θ₁) = n₂ * sin(θ₂), where:
The refractive index of air is approximately 1, and the refractive index of water is approximately 1.33. Given the angle of incidence in air is 30º:
Using Snell's Law:
1 * sin(30º) = 1.33 * sin(θ₂)
You will find:
sin(θ₂) = sin(30º) / 1.33
sin(θ₂) ≈ 0.5 / 1.33
sin(θ₂) ≈ 0.375
Now, solve for θ₂ by taking the inverse sine (arcsin):
θ₂ ≈ arcsin(0.375)
θ₂ ≈ 22.09º
Thus, when a light ray passes from air into water at an angle of 30º from the normal in air, it will make an angle less than 30º from the normal in water, approximately 22.09º. This is because the light ray bends toward the normal as it enters a denser medium (water).
Question 3 Rapport
Use the diagram above to answer the question that follows
The zone labelled II is called
Détails de la réponse
The zone labelled II is called the littoral zone.
To explain: The littoral zone is a part of a body of water that is close to the shore. It is typically characterized by abundant sunlight and nutrient availability, making it a highly productive area for aquatic plants and animals. This zone supports various forms of life such as algae, small fish, and invertebrates. The key feature of the littoral zone is its proximity to the shoreline, where sunlight can penetrate to the bottom, allowing for photosynthesis to occur.
Question 4 Rapport
The formation of cilia and flagella in living cells is carried out with the help of
Détails de la réponse
The formation of cilia and flagella in living cells is primarily carried out with the help of **centrioles**.
Here's a simple explanation:
Centrioles are cylindrical structures made up of microtubules. They are found in eukaryotic cells and play a critical role in cell division and the organization of the cell's cytoskeleton. However, their role extends beyond this to the formation of the basal bodies which seed the growth of cilia and flagella.
Cilia and flagella are microscopic, hair-like structures that protrude from the surface of certain eukaryotic cells. They are primarily involved in movement. Cilia often work like tiny oars, moving fluid across the cell's surface or propelling single-celled organisms. Flagella are typically longer and move in a whip-like fashion to propel cells, such as sperm cells.
Here's how centrioles contribute to the formation of these structures:
1. **Basal Body Formation**: Each cilium or flagellum grows out from a structure known as a basal body. The basal body is derived from the centrioles. During this process, a centriole migrates to the cell's surface and acts as a nucleation site for the growth of microtubules, which in turn form the structural core of cilia and flagella.
2. **Microtubule Organization**: The centrioles help organize microtubules in a "9+2" arrangement, which is characteristic of cilia and flagella. This refers to nine pairs of microtubules forming a ring around two central microtubules, giving these structures both stability and flexibility for movement.
Thus, centrioles are crucial as they provide the groundwork for the formation and proper functioning of cilia and flagella. They ensure that these structures are assembled correctly and are able to carry out their roles in cell movement and fluid transport.
Question 5 Rapport
The fourth overtone of a closed pipes is 900Hz, its fundamental frequency is
Détails de la réponse
To solve this problem, let's first understand how sound works in a closed pipe. A closed pipe has one end closed and another end open. Sound waves inside such a pipe create standing waves, where nodes (points of no movement) and antinodes (points of maximum movement) are formed.
For a closed pipe, the fundamental frequency (also called the first harmonic) has one node at the closed end and one antinode at the open end. The wavelength is four times the length of the pipe.
The overtone sequence for a closed pipe includes only odd harmonics: 1st (fundamental), 3rd, 5th, 7th, etc. The nth overtone is the 2nth + 1 harmonic. The equation for the frequency of a harmonic in a closed pipe is:
f_n = n * f_1, where f_n is the frequency of the nth harmonic and f_1 is the fundamental frequency
In this case, the fourth overtone corresponds to the 9th harmonic because 2 * 4 + 1 = 9. Therefore, we have:
900 Hz = 9 * f_1
To find the fundamental frequency (f_1), we solve for f_1:
f_1 = 900 Hz / 9
f_1 = 100 Hz
Therefore, the fundamental frequency is 100 Hz.
Question 6 Rapport
Which of these gas laws is equivalent to workdone
Détails de la réponse
To understand which of these gas laws is equivalent to work done, we must first understand the basic concept of work in the context of gases. For gases, work is done when there is a change in volume under pressure, typically expressed as W = P ΔV, where W is work, P is pressure, and ΔV is the change in volume.
Let's consider the given gas laws:
Among these, Boyle's law relates directly to work done because it involves a change in volume at constant temperature, implying that work occurs as a gas expands or compresses. The equation P₁V₁ = P₂V₂ is foundational for calculating work done in reversible processes, which aligns with the expression for work done on a gas, W = P ΔV. Thus, **Boyle's law** is most directly connected to the concept of work done on a gas.
Question 7 Rapport
Find the value of a capacitor with voltage 5V and 30C.
Détails de la réponse
To find the value of the capacitance, we need to use the formula for capacitance:
Capacitance (C) = Charge (Q) / Voltage (V)
In this problem, the charge (Q) is given as 30 Coulombs (C) and the voltage (V) is 5 Volts (V). We can plug these values into the formula:
C = 30 C / 5 V
Calculating the above expression gives:
C = 6 Farads (F)
Therefore, the value of the capacitor is 6 Farads.
Question 8 Rapport
When thermal energy in a solid is increased, the change in state is called
Détails de la réponse
When the thermal energy in a solid is increased, the solid particles gain energy and begin to vibrate more vigorously. As the temperature rises, these particles eventually have enough energy to overcome the forces holding them in their fixed positions. This leads to a change of state from a solid to a liquid. This process is known as melting.
To further understand this, imagine an ice cube. As it absorbs heat, it gains energy, and the ice (which is a solid) starts to turn into water (which is a liquid). This transition is what we refer to as melting.
Thus, the term that describes this change of state, when a solid is heated and turns into a liquid, is melting.
Question 9 Rapport
Electrolysis can be investigated using
Détails de la réponse
When investigating electrolysis, the most relevant instrument from the list provided is the Voltameter. This is because the voltameter is specifically designed to measure the amount of substance that is deposited or consumed at electrodes during the electrolysis of an electrolyte. It functions based on the chemical change associated with the electric current passing through the electrolyte.
Here is a simple explanation of how electrolysis works and why a voltameter is useful:
Electrolysis is the process of using electricity to cause a chemical reaction, which is usually a decomposition reaction. This involves passing an electric current through an electrolyte (a substance containing free ions). These ions migrate towards electrodes, resulting in chemical changes. The key aspect to measure during electrolysis is the amount of material (e.g., metal or gas) that is deposited at the electrodes.
The Voltameter helps in understanding electrolysis because:
Voltmeter, Ammeter, and Galvanometer are not used primarily for investigating electrolysis:
Question 10 Rapport
Two capacitors of 0.0003μF and 0.0006μF are connected in series, find their combined capacitance.
Détails de la réponse
When capacitors are connected in series, the formula to find their combined capacitance \(C_{\text{total}}\) is given by:
\[ \frac{1}{C_{\text{total}}} = \frac{1}{C_1} + \frac{1}{C_2} \]
where \(C_1\) and \(C_2\) are the capacitances of the individual capacitors. In this case, \(C_1 = 0.0003 \, \mu\text{F}\) and \(C_2 = 0.0006 \, \mu\text{F}\).
First, calculate the reciprocal of each capacitance:
\[ \frac{1}{C_1} = \frac{1}{0.0003} \]
\[ \frac{1}{C_2} = \frac{1}{0.0006} \]
Calculating each value:
\[ \frac{1}{0.0003} = \frac{10^6}{3} \] and \[ \frac{1}{0.0006} = \frac{10^6}{6} \]
Now, add these values together:
\[ \frac{1}{C_{\text{total}}} = \frac{10^6}{3} + \frac{10^6}{6} = \frac{10^6 \times 2}{6} + \frac{10^6 \times 1}{6} = \frac{10^6 \times 3}{6} = \frac{10^6}{2} \]
Finally, take the reciprocal of the resulting value to find \(C_{\text{total}}\):
\[ C_{\text{total}} = \frac{2}{10^6} = 0.0002 \, \mu\text{F} \]
So, the combined capacitance of the two capacitors in series is 0.0002 μF.
Question 11 Rapport
If a charge ion goes through a combined electric field E and magnetic field B, the resultant emergent velocity of the ion is
Détails de la réponse
The resultant emergent velocity of a charged ion moving through combined electric and magnetic fields can be derived from the condition where the electric force equals the magnetic force. This gives us the formula for the velocity v:
q E = qvB
v = EB (q will cancel out)
NOTE: When both fields are present, for the ion to move without deflection, the electric force must equal the magnetic force.
Question 12 Rapport
The velocity ratio of an inclined plane at 60º to the horizontal is
Détails de la réponse
The concept of an inclined plane is all about simplifying the forces involved in moving or holding a load. The **velocity ratio (VR)** for an inclined plane is defined as the ratio of the distance moved by the effort to the distance moved by the load. This can also be expressed in terms of the lengths involved in the triangle made by the inclined plane.
For an inclined plane placed at an angle **θ** to the horizontal, the velocity ratio is given by the formula:
VR = 1/sin(θ)
Given that the inclined plane is at an angle of **60º**:
First, find the sine of 60º:
sin(60º) = √3/2 (approximately 0.866)
Now, substitute this value into the formula for VR:
VR = 1/sin(60º) ≈ 1/0.866 ≈ 1.155
The **velocity ratio** for an inclined plane at **60º** to the horizontal is **approximately 1.155**.
Question 13 Rapport
When a charged ebonite rod is brought near a charged glass rod, there will be
Détails de la réponse
When a charged ebonite rod is brought near a charged glass rod, there will be attraction. This is because charged objects obey the fundamental principle of electrostatics, which states that opposite charges attract each other while like charges repel each other.
An ebonite rod typically acquires a negative charge when rubbed with fur, as it gains electrons. In contrast, a glass rod usually acquires a positive charge when rubbed with silk, as it loses electrons. Therefore, when these two objects, one negatively charged and the other positively charged, are brought near each other, the opposite charges will attract.
Question 14 Rapport
A wheelbarrow inclined at 60º to the horizontal is pushed with a force of 150N. What is the horizontal component of the applied force
Détails de la réponse
When you push a wheelbarrow inclined at an angle to the horizontal, the applied force can be divided into two components: a **horizontal component** and a **vertical component**. To find the horizontal component of the force, you need to use the concept of resolving vectors.
The force of 150N is acting at an angle of 60º to the horizontal. The horizontal component of this force can be calculated using the cosine of the angle. The formula to determine the horizontal component \( F_{\text{horizontal}} \) is given by:
Fhorizontal = Fapplied \times \cos(\theta)
Where:
Substitute the values into the formula:
Fhorizontal = 150N \times \cos(60º)
We know that \(\cos(60º)\) equals 0.5.
Therefore:
Fhorizontal = 150N \times 0.5 = 75N
Thus, the **horizontal component** of the applied force is 75N.
Question 15 Rapport
An ideal transformer has
Détails de la réponse
An ideal transformer is a hypothetical concept used in electrical engineering to simplify the analysis of real transformers. In an ideal transformer, several assumptions are made to avoid losses and inefficiencies. Here's what an ideal transformer has:
No flux leakage: In an ideal transformer, it is assumed that all the magnetic flux generated in the primary coil is perfectly linked with the secondary coil. This means there is no flux leakage. This assumption ensures maximum efficiency, as all the energy is transferred from the primary to the secondary coil without losses.
Let's briefly discuss the other concepts to understand why they don't pertain to an ideal transformer:
Maximum primary resistance: In an ideal transformer, the resistance of the windings is assumed to be zero. If the primary has maximum resistance, it would result in power loss due to the resistance, contradicting the idea of an ideal transformer.
Hysteresis: This refers to the energy loss that happens in the core material due to the cyclic magnetization and demagnetization processes. An ideal transformer assumes there is no hysteresis loss, meaning the core material does not absorb any energy during these cycles.
Eddy current: These are loops of electric current induced within conductors by a changing magnetic field, which can cause significant energy loss. In an ideal transformer, it is assumed that there are no eddy currents, hence no energy loss due to this effect.
In summary, an ideal transformer is characterized by having no flux leakage, and it assumes that there are no losses due to resistance, hysteresis, or eddy currents. This makes the ideal transformer a perfect, lossless device for the purposes of theoretical analysis.
Question 16 Rapport
The charge of magnitude 1.6 x 10 −19 C is placed in a uniform electric field of intensity 1200Vm−1 . Calculate its acceleration, if the mass of the charge is 9.1 x 10−31 kg
Détails de la réponse
To calculate the acceleration of a charge in an electric field, we start by determining the force acting on the charge. The force \( F \) experienced by a charge \( q \) in a uniform electric field \( E \) is given by the equation:
F = q * E
We are given:
Substituting these values into the equation for force:
F = 1.6 x 10-19 C * 1200 V/m
This results in:
F = 1.92 x 10-16 N
Next, we use Newton’s second law of motion to find the acceleration \( a \) of the charge. This law is given as:
F = m * a
Rearranging for \( a \), we have:
a = F / m
We know:
Substituting these values in the equation for acceleration:
a = \(\frac{1.92 x 10^{-16} N}{9.1 x 10^{-31} kg}\)
Calculating the above expression gives:
a ≈ 2.11 x 1014 ms-2
Therefore, the acceleration of the charge is approximately 2.11 x 1014 ms-2.
Question 17 Rapport
The property by which a material returns to its original shape after the removal of force is called
Détails de la réponse
The property by which a material returns to its original shape after the removal of force is called Elasticity.
Let's break it down:
Elasticity: This is a property of a material that allows it to return to its original shape or size after the force that caused deformation is removed. Think of a rubber band—you can stretch it, but once you let it go, it snaps back to its initial shape.
Ductility: This property refers to a material's ability to be stretched into a wire. For example, materials like copper are ductile because they can be drawn into thin wires without breaking.
Malleability: This is a material's ability to withstand deformation under compressive stress. It is the property that allows metals to be hammered or rolled into thin sheets. Gold is a good example of a malleable metal.
Plasticity: This property describes the material's ability to undergo permanent deformation without breaking. When a plastic region is reached, the material will not return to its original shape after the removal of force.
Therefore, when we speak of a material returning to its original shape after the removal of force, we are specifically referring to Elasticity.
Question 18 Rapport
The tangential force acting on an object that opposes it from sliding freely on the adjacent surface is called
Détails de la réponse
The tangential force acting on an object that opposes it from sliding freely on the adjacent surface is called the friction force.
Let me explain each of the options to clarify why friction force is the correct answer:
In summary, friction force is the force that acts to oppose sliding between surfaces in contact and acts tangentially, making it the correct answer.
Question 19 Rapport
The distance between two successive crests of a water wave is 0.25m. If a particle on the surface of the water makes four complete vertical oscillations in one second. Calculate the speed of the wave.
Détails de la réponse
To calculate the speed of the wave, we need to understand some fundamental wave properties: **wavelength**, **frequency**, and **wave speed**.
1. **Wavelength (\( \lambda \))**: The wavelength is the distance between two successive crests of a wave. In this case, the wavelength is given as **0.25 meters**.
2. **Frequency (\( f \))**: Frequency is the number of complete oscillations or cycles that occur per second. It is given that a particle on the surface of the water makes **four complete vertical oscillations in one second**. So, the frequency is **4 Hz (hertz)**.
3. **Wave Speed (\( v \))**: The speed of a wave is calculated using the formula:
\( v = f \times \lambda \)
Where:
\( v \) is the wave speed,
\( f \) is the frequency, and
\( \lambda \) is the wavelength.
Substitute the given values into the formula:
\( v = 4 \text{ Hz} \times 0.25 \text{ m} \)
\( v = 1 \text{ m/s} \)
Therefore, the **speed of the wave** is 1 m/s.
Question 20 Rapport
Two points on a velocity-time graph have coordinates (2s, 5m/s) and (4s, 15m/s). Calculate the mean acceleration
Détails de la réponse
The mean acceleration of an object is determined by the change in velocity over the change in time. This is given by the formula:
Mean Acceleration (a) = (Final Velocity - Initial Velocity) / (Final Time - Initial Time)
From the velocity-time graph, we have the following points:
Initial Point: (2s, 5m/s)
Final Point: (4s, 15m/s)
Here, the Initial Velocity is 5m/s, the Final Velocity is 15m/s, the Initial Time is 2s, and the Final Time is 4s.
Plug these values into the formula:
Mean Acceleration (a) = (15m/s - 5m/s) / (4s - 2s)
Simplifying this, we get:
Mean Acceleration (a) = 10m/s / 2s = 5m/s²
The mean acceleration is therefore 5.0 m/s².
Question 21 Rapport
Newton's law of cooling is valid only for a
Détails de la réponse
Newton's Law of Cooling states that the rate of heat loss of an object is directly proportional to the difference in temperature between the object and its surroundings, provided that this temperature difference is small.
Therefore, this law is only valid within a small temperature range.
Question 22 Rapport
As per Faraday's laws of electromagnetic induction, an e.m.f is induced in a conductor whenever
Détails de la réponse
According to Faraday's laws of electromagnetic induction, an electromotive force (e.m.f) is induced in a conductor whenever it **cuts magnetic flux**. This means that for an e.m.f to be induced, the conductor must move in such a way that it intersects the magnetic lines of force. It is the relative motion between the conductor and the magnetic field that leads to the change in magnetic flux, resulting in the induction of e.m.f.
Let's explore why this is the correct answer using reasoning:
Therefore, the phenomenon where a conductor cuts magnetic flux is essential for electromagnetic induction as per Faraday's laws.
Question 23 Rapport
Calculate the upthrust on a spherical ball of volume 4.2 x 10−4 m3 when totally immersed in a liquid of density 1028kgm−3
Détails de la réponse
Upthrust(Force) = volume of object x density of liquid x g = V x ρ x g
U = 4.2 x 10−4 x 1028 x 10 ≊ 4.3N
Question 24 Rapport
The mechanical advantage of the machine shown above
Détails de la réponse
Mechanical advantage of a machine = LOADEFFORT
In this case of a wedge, we can consider the dimensions given:
Load distance (height of the machine): 15 cm
Effort distance (movement of the effort): 0.5 cm
M.A = 150.5 = 30.0
Question 25 Rapport
The energy in a moving car is an example of
Détails de la réponse
The energy in a moving car is an example of kinetic energy.
To explain simply, **energy** is the ability to do **work** or cause **change**. There are different forms of energy, and **kinetic energy** is one of them. It is defined as the energy possessed by an object due to its motion.
When a car is moving, it possesses **kinetic energy** because its components are in **motion**. This motion energy allows the car to do tasks, such as transporting people or goods from one place to another. The faster the car moves, the greater its **kinetic energy**, and thus it can make a larger impact or do more work.
In contrast, energy forms like **mechanical energy** is a combination of both kinetic and potential energy; **electrical energy** is associated with electrical charge movement, while **potential energy** is related to the position or condition of an object (like a car parked on a hill). Therefore, the specific type of energy from a moving car is **kinetic energy**.
Question 26 Rapport
A blacksmith heated a metal whose cubic expansivity is 3.9 x 10−6 K−1 . Calculate the area expansivity.
Détails de la réponse
To find the area expansivity of a metal when given its cubic expansivity, you should understand the relationship between linear, area, and cubic expansivity.
Cubic expansivity (\( \beta \)) is defined as the fractional change in volume per change in temperature, and is given by the formula:
\[ \Delta V = \beta V \Delta T \]
Area expansivity (\( \alpha_{A} \)) corresponds to the fractional change in area per change in temperature and can be derived from the linear expansivity (\( \alpha \)). The relationship between these expansivities is as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = 2 \times \text{Linear Expansivity (\( \alpha \))} \]
The cubic expansivity (\( \beta \)) is related to the linear expansivity by:
\[ \text{Cubic Expansivity (\( \beta \))} = 3 \times \text{Linear Expansivity (\( \alpha \))} \]
Thus, based on these relationships, we can express the area expansivity in terms of the cubic expansivity:
\(\text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times \text{Cubic Expansivity (\( \beta \))}
Given that the cubic expansivity \( \beta \) is \( 3.9 \times 10^{-6} \, \text{K}^{-1} \):
The area expansivity can be calculated as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times 3.9 \times 10^{-6} \, \text{K}^{-1} = 2.6 \times 10^{-6} \, \text{K}^{-1} \]
Therefore, the **correct answer** is **2.6 x 10^{-6} K^{-1}**.
Question 27 Rapport
Bifocal lens is used to correct the eye defect of
Détails de la réponse
Bifocal lenses are primarily used to correct the eye defect known as presbyopia. As people age, the lens of the eye naturally loses its flexibility, making it difficult to focus on objects that are close up. This condition is known as presbyopia. A bifocal lens is designed with two different optical powers to accommodate this need. The upper part of the lens is usually crafted for distance vision, while the lower segment is designed for near vision tasks, such as reading.
Astigmatism is a different eye condition caused by irregular curvature of the cornea or lens, resulting in blurred or distorted vision at all distances. This condition is typically corrected with cylindrical lenses rather than bifocals.
Hypermetropia, commonly known as farsightedness, is a condition where distant objects can be seen more clearly than near ones. Simple convex lenses are usually used for this correction.
Myopia, or nearsightedness, is a condition where nearby objects are seen clearly, while distant objects appear blurry. Concave lenses are generally used to correct this condition.
In summary, bifocal lenses are specifically designed to address the challenges of focusing at different distances simultaneously, making them ideal for managing presbyopia.
Question 28 Rapport
Rainbow is formed when sunlight undergoes
Détails de la réponse
A rainbow is formed through a combination of three processes: reflection, refraction, and dispersion. Let's break down each process to understand how a rainbow forms:
1. Refraction: When sunlight enters a raindrop, it bends or changes direction. This bending of light is known as **refraction**. Different colors of sunlight bend by different amounts because they have different wavelengths.
2. Reflection: Once inside the raindrop, the light gets reflected off the inside surface of the drop. This reflection sends the light back out of the raindrop at different angles.
3. Dispersion: As the light exits the raindrop, it bends again (refraction). Because each color bends by a different amount, the sunlight is spread out into its component colors, creating a spectrum. This spreading into a spectrum is called **dispersion**.
All three processes contribute to the formation of a rainbow. The combination of **refraction, reflection, and dispersion** results in the beautiful arc of colors that we see in the sky.
Question 29 Rapport
In a solar panel, solar beam is concentrated by using
Détails de la réponse
In a solar panel system, the type of mirror used to concentrate solar beams is the Concave Mirror.
Explanation:
A concave mirror is a type of mirror that curves inward, like the inside of a bowl. This shape is very effective at focusing light. When sunlight hits a concave mirror, the mirror's shape causes the light beams to converge, or come together, at a single point known as the focus. This concentrated light can then be used to generate heat or electricity more efficiently.
Why not the others?
A convex mirror curves outward and disperses light beams rather than concentrating them.
A plane mirror has a flat surface and reflects light at the same angle it receives it, meaning it doesn't concentrate the beams.
A triangular mirror is not typically used in solar applications for concentrating light as its shape is not conducive to focusing beams effectively.
Therefore, a concave mirror is best suited for concentrating solar beams in solar panel systems.
Question 30 Rapport
The food nutrient with the highest energy value is
Détails de la réponse
Fat is the food nutrient with the highest energy value, providing 9 calories per gram, while carbohydrates and proteins provide 4 calories per gram.
Fat is the body's most concentrated source of energy, providing more than twice as much potential energy as carbohydrates or proteins.However, carbohydrates burn fastest in metabolism. Fats are a type of lipid. Lipids are a group of organic compounds that are insoluble in water but soluble in organic solvents. Fats are solid at room temperature, while oils are liquid at room temperature.
Therefore, the correct answer is option C.
Question 31 Rapport
In a Hare's apparatus, the height of water and a liquid X are 0.3m and 0.5m respectively. The relative density of x is?
Détails de la réponse
For Hare's apparatus
Relative density = hwhl
Given: height of liquid = 0.5cm, height of water = 0.3cm
Relative density = 0.30.5 = 0.6
Question 32 Rapport
Calculate the depth of a swimming pool if the apparent depth is 10cm. ( Refractive index of water = 1.33 )
Détails de la réponse
To calculate the real depth of a swimming pool given the apparent depth, we can use the concept of refraction of light. When light passes from one medium to a denser medium, it bends towards the normal. This bending effect causes objects submerged in water to appear closer to the surface than they actually are. The formula to relate these depths is given by:
Real Depth = Apparent Depth × Refractive Index
Given the problem:
Using the formula:
Real Depth = 10 cm × 1.33
Calculating the above:
Therefore, the depth of the swimming pool is 13.3cm.
Question 33 Rapport
The equivalent capacitance of the capacitors in the circuit above
Détails de la réponse
apacitance in parallel = one at the top + one under = 2C
The two in the middle are in series = C2
The equivalent capacitance of the capacitors in the circuit above = C2 + 2C = 52 C
Question 34 Rapport
A monochromatic light is one that
Détails de la réponse
A monochromatic light is one that has a single wavelength or color. This means that it consists of light waves that all have the same frequency, resulting in a uniform appearance without any variation.
Question 35 Rapport
The dimension of power is
Détails de la réponse
The dimension of power in physics is expressed in terms of the base units of mass (M), length (L), and time (T). Power is the rate at which work is done or energy is transferred over time, and it has the unit of watt (W) which is equivalent to one joule per second.
To derive the dimension of power:
1. Work has the dimension of energy, which is force applied over a distance. The dimension of work (or energy) is M L2 T-2 because force has the dimension M L T-2 and distance adds another L.
2. Since power is work done per unit time, you would divide the dimension of work by time (T).
Thus, the dimensional formula for power is:
M L2 T-3
Question 36 Rapport
The land and sea breeze is attributed to
Détails de la réponse
The phenomenon of land and sea breeze is primarily attributed to convection.
To understand this, let's first look at what land and sea breezes are:
Land Breeze: At night, the land cools down faster than the sea. The cooler, denser air from the land moves towards the sea, and this is known as a land breeze.
Sea Breeze: During the day, the land heats up more quickly than the sea. The warmer, lighter air over the land rises, and the cooler air from the sea moves in to take its place. This movement of air from the sea to the land is known as a sea breeze.
Both of these processes involve the movement of air due to differences in temperature and density, which is essentially the process of convection.
Convection is the transfer of heat through a fluid (like air or water) and is responsible for moving air masses and creating these breezes. The warm air, being less dense, rises, and the cooler, denser air moves in to replace it.
In contrast, conduction is the transfer of heat through a solid material, and radiation is the transfer of heat in the form of electromagnetic waves, neither of which primarily drive the processes of these breezes, making convection the key player.
Question 37 Rapport
A thick glass tumbler cracks when boiling water is poured into it because
Détails de la réponse
When boiling water is poured into a thick glass tumbler, the inner surface of the glass is suddenly exposed to a much higher temperature compared to the outer surface. Glass is a poor conductor of heat, which means it does not transfer heat quickly. As a result, the inside of the tumbler becomes hot and attempts to **expand quickly**, while the outside remains cooler and does not expand at the same rate.
**This uneven expansion** creates tension between the inner and outer layers of the glass. The inner surface tries to expand but is constrained by the cooler, rigid outer surface, which isn't expanding as much or as quickly. This stress and tension can lead to cracking.
Therefore, the correct reason a thick glass tumbler cracks when boiling water is poured into it is because **the inside expands more rapidly than the outside.**
Question 38 Rapport
What is the colour of red rose under a blue light?
Détails de la réponse
To understand the color of a red rose under a blue light, we need to consider how we perceive color. Objects appear colored because they reflect certain wavelengths of light. A red rose appears red in white light because it reflects red wavelengths and absorbs others.
When you shine blue light on a red rose, the situation changes. A blue light primarily contains blue wavelengths. Since the red rose does not have red wavelengths to reflect anymore, and it cannot reflect blue light (as it absorbs it), the rose will appear to be the absence of any reflected wavelength visible to our eyes.
This means the rose will appear black under blue light, as black is perceived when no visible light is reflected into our eyes. Thus, the color of the red rose under a blue light is black.
Question 39 Rapport
Mouth part adapted for piercing and sucking is found in
Détails de la réponse
The mouthpart adapted for piercing and sucking is found in the mosquito. Mosquitoes have a specialized mouth structure called a proboscis. This proboscis is long and slender, allowing mosquitoes to puncture the skin of their hosts and suck blood. The proboscis is a complex structure that contains several needle-like parts that make the piercing and sucking process efficient and effective.
Question 40 Rapport
Calculate the value of electric field intensity due to a charge of 4μC if the force due to the charge is 8N
Détails de la réponse
To calculate the electric field intensity due to a charge, we need to use the formula:
Electric Field Intensity (E) = Force (F) / Charge (q)
In this problem, we are given that the force (F) is 8 Newtons (N) and the charge (q) is 4 microcoulombs (μC). First, we need to convert the charge from microcoulombs to coulombs:
1 microcoulomb (μC) = 1 x 10-6 coulombs (C)
Therefore, 4 μC = 4 x 10-6 C.
Now we can use the formula to find the electric field intensity:
E = F / q
E = 8 N / (4 x 10-6 C)
E = 8 / 4 x 106
E = 2 x 106
Thus, the value of the electric field intensity is 2 x 106 N/C.
Souhaitez-vous continuer cette action ?