▶️ Answer/Explanation
Detailed solution:
First, determine the scale increment: there are $5$ divisions between $10$ and $20$, so each small mark represents $2\text{ cm}^3$.
The level of the liquid (the bottom of the meniscus) is three small divisions above the $10\text{ cm}^3$ mark.
Calculating the total volume: $10\text{ cm}^3 + (3 \times 2\text{ cm}^3) = 16\text{ cm}^3$.
Since the scale allows for such precision, the reading is exactly $16.0\text{ cm}^3$.
This matches Option C.
▶️ Answer/Explanation
Detailed solution:
Speed is a scalar quantity defined as distance per unit time ($v = \frac{s}{t}$), having only magnitude.
Velocity is a vector quantity, defined as speed in a specified direction.
Option A is incorrect because both can be $0$ when an object is at rest.
Option B is incorrect as the magnitude of velocity can equal speed in straight-line motion.
Option D is incorrect because both quantities share the same $SI$ unit of $m/s$.
Option C correctly identifies that velocity is simply speed with the addition of direction.
▶️ Answer/Explanation
Detailed solution:
To find the order, we calculate the average speed for each race using $v = \frac{s}{t}$:
Race 1: $v_{1} = \frac{100\text{ m}}{12\text{ s}} \approx 8.33\text{ m/s}$
Race 2: $v_{2} = \frac{150\text{ m}}{17\text{ s}} \approx 8.82\text{ m/s}$
Race 3: $v_{3} = \frac{200\text{ m}}{25\text{ s}} = 8.00\text{ m/s}$
Comparing these values: $8.00\text{ m/s} < 8.33\text{ m/s} < 8.82\text{ m/s}$.
The order from lowest to highest speed is Race 3, then Race 1, then Race 2.
This corresponds to the sequence $3 \rightarrow 1 \rightarrow 2$.
▶️ Answer/Explanation
Detailed solution:
The weight of an object is calculated using the formula W=m×g, where m is the mass in kg and g is the acceleration of free fall.
According to the syllabus, the value of g near the surface of the Earth is approximately 9.8 m/s 2 .
For Row A, the weight is 2.00 kg×9.8 m/s 2 =19.6 N, which matches the table.
In Row C, the weight should be 10.0×9.8=98.0 N, making the given 9.80 N incorrect.
Rows B and D incorrectly divide the mass by g rather than multiplying, resulting in values near 1.02 and 2.04.
Therefore, Row A provides the only mathematically correct relationship between mass and weight.
▶️ Answer/Explanation
Detailed solution:
An object floats if its density is less than the density of the liquid ($1.4\text{ g/cm}^{3}$).
Density is calculated using $\rho = \frac{m}{V}$.
$\rho_{A} = \frac{1.0}{0.5} = 2.0\text{ g/cm}^{3}$ (Sinks)
$\rho_{B} = \frac{2.0}{3.0} \approx 0.67\text{ g/cm}^{3}$ (Floats)
$\rho_{C} = \frac{6.0}{4.0} = 1.5\text{ g/cm}^{3}$ (Sinks)
$\rho_{D} = \frac{9.0}{6.0} = 1.5\text{ g/cm}^{3}$ (Sinks)
Only object B has a density lower than $1.4\text{ g/cm}^{3}$, so it is the only one that floats.
▶️ Answer/Explanation
Detailed solution:
The car starts from rest and accelerates due to a constant driving force. As speed increases, the resistive forces (drag and friction) also increase because they are proportional to speed. According to $F_{resultant} = F_{driving} – F_{resistive}$, the net force decreases as the resistive force grows. Eventually, the resistive force increases until it equals the driving force, resulting in $F_{resultant} = 0$. At this point, the acceleration $a = \frac{F}{m}$ becomes $0$, and the car reaches a constant maximum speed (terminal velocity).
▶️ Answer/Explanation
Detailed solution:
When a person lies on the bed, their weight exerts a force $F$ that compresses the springs in the mattress.
This compression causes a change in the shape of the springs, resulting in work being done to deform them.
The energy transferred by this work is stored as elastic (strain) energy within the material of the springs.
According to the syllabus, the energy in an elastic store is calculated using $E_{e} = \frac{1}{2}kx^{2}$, where $x$ is the compression.
As the compression $x$ increases from zero, the elastic energy store of the mattress must increase.
Other stores like chemical or kinetic do not increase as the mattress remains stationary and no chemical reaction occurs.
▶️ Answer/Explanation
Detailed solution:
Chemical energy is energy stored in the bonds of chemical compounds, which is released during a chemical reaction (like combustion).
Biofuel, coal, and oil are all forms of fuel that release energy through burning, meaning they are stores of chemical energy.
Nuclear fuel, such as uranium, does not release energy through chemical bonds but through nuclear fission or fusion.
In these processes, energy is released from the nucleus of the atom, which is defined as a store of nuclear energy.
Therefore, nuclear fuel is the only resource listed that does not contain a store of chemical energy.
Option C is the correct choice as it identifies nuclear fuel as a non-chemical energy store.
▶️ Answer/Explanation
Detailed solution:
The work done against gravity is equal to the gain in gravitational potential energy, calculated as W=ΔE p =mgh.
The total mass m is the number of tiles multiplied by the mass of one tile: 20×1.2 kg=24 kg.
Using the standard value for acceleration of free fall g=9.8 m/s 2 (as per the 0625 syllabus) and height h=15 m.
Substituting the values: W=24 kg×9.8 m/s 2 ×15 m=3528 J.
Rounding to two significant figures to match the provided options gives 3500 J.
Thus, the work done by the person on the tiles is approximately 3500 J, which corresponds to Option D.
▶️ Answer/Explanation
Detailed solution:
Pressure is defined as the force exerted per unit area, expressed by the formula p= A F .
In this context, the force F is equal to the weight W of the brick.
To increase the pressure p, one must either increase the numerator (weight) or decrease the denominator (contact area).
An increase in weight results in a greater force being applied downward onto the surface.
A decrease in the contact area concentrates that force over a smaller region, further raising the pressure.
Therefore, the combination of increasing the weight and decreasing the area (Option B) will always result in a higher pressure.
▶️ Answer/Explanation
Detailed solution:
The substances start as solids; the first horizontal section on a heating curve represents the melting point where the temperature remains constant during the phase change.
By observing the vertical axis (temperature), the plateau for substance Y occurs at a lower position than the plateau for substance X.
This indicates that the temperature at which substance Y melts, T m(Y) , is less than the melting temperature of substance X, T m(X) .
Since the graph only shows the transition from solid to liquid, we cannot determine boiling points from this data.
Therefore, the graph confirms that substance Y has a lower melting point than substance X.
Option D correctly identifies this relationship based on the provided temperature-time coordinates.
▶️ Answer/Explanation
Detailed solution:
Both liquids and gases are classified as fluids because their particles can move past one another, giving them the ability to flow.
When a liquid turns into a gas, the particles move much further apart, causing the volume to increase significantly.
Gases are highly compressible due to the large spaces between particles, whereas liquids are virtually incompressible.
While both take the shape of their container, a gas expands to fill the entire available space unlike a liquid.
Therefore, the only property that remains fundamentally the same for both states in this context is their ability to flow.
▶️ Answer/Explanation
Detailed solution:
Iron is a solid, meaning its particles are packed in a regular lattice with very small gaps between them. Conversely, oxygen is a gas where the separation between particles is much larger than the particle size itself. Compression requires reducing the empty space between particles; since iron particles are already extremely close together, there is negligible room for further reduction. In oxygen, the large intermolecular distances allow for significant compression under pressure. While mass and magnetism are properties of iron, they do not explain compressibility. Furthermore, at the same temperature, both substances have the same average kinetic energy, as defined by the relation $E_{k} \propto T$.
▶️ Answer/Explanation
Detailed solution:
When the plunger is moved out, the volume $V$ of the gas increases while the temperature $T$ remains constant.
According to Boyle’s Law, $pV = \text{constant}$, so an increase in volume leads to a decrease in pressure $p$.
In terms of the kinetic particle model, the gas particles are now spread out over a larger space.
As a result, the particles hit the walls of the syringe less often, meaning the frequency of collisions decreases.
Since pressure is defined as the force per unit area, fewer collisions per second result in a lower pressure.
Therefore, Row A correctly identifies that the pressure decreases because particles collide with the walls less frequently.
▶️ Answer/Explanation
Detailed solution:
Evaporation is the process where a liquid changes into a gas at temperatures below the boiling point. In a liquid, molecules move at various speeds, meaning they have different amounts of kinetic energy $E_{k}$. Molecules at the surface with higher-than-average energy can overcome the attractive forces of neighboring molecules. Consequently, these more-energetic molecules escape the liquid phase to become a gas. As a result, the average $E_{k}$ of the remaining molecules decreases, leading to the cooling of the liquid. Option C correctly identifies that it is the more-energetic molecules that leave the surface.
▶️ Answer/Explanation
Detailed solution:
Thermal conduction is the process where energy is transferred through a material. A better thermal conductor transfers energy faster, meaning the wax will reach its melting point in a shorter amount of time ($t$).
According to the bar chart, the times recorded are: $t_W \approx 14\text{ s}$, $t_X \approx 45\text{ s}$, $t_Y \approx 77\text{ s}$, and $t_Z \approx 85\text{ s}$.
Since $t_X < t_Y$, material $X$ conducts heat to the pin faster than material $Y$ does.
Therefore, $X$ is a better thermal conductor than $Y$, making statement A correct.
Statements B, C, and D are incorrect because they suggest materials with higher time values ($Y$ and $Z$) are better conductors than those with lower time values ($W$ and $X$).
▶️ Answer/Explanation
Detailed solution:
Thermal energy transfer via radiation depends heavily on the surface characteristics of an object.
Darker colours are better emitters than lighter colours; thus, black surfaces emit more than white ones.
Texture also plays a role: dull or matt surfaces are more efficient at emitting infrared radiation than shiny, reflective surfaces.
Since the containers are at 80 °C and the room is at 20 °C, they will lose energy to the surroundings.
A dull black surface is the most effective configuration for both absorbing and emitting thermal radiation.
Consequently, the container with the dull black surface will emit energy at the greatest rate.
▶️ Answer/Explanation
Detailed solution:
First, calculate the frequency f, which is the number of waves passing a point per second: f= 10 s 4.0 waves =0.40 Hz.
The relationship between wave speed v, frequency f, and wavelength λ is given by the wave equation: v=fλ.
Rearrange the formula to solve for wavelength: λ= f v .
Substitute the given speed v=2.0 m/s and the calculated frequency into the equation: λ= 0.40 2.0 .
This results in a wavelength of λ=5.0 m.
Therefore, the correct wavelength of the water wave is 5.0 m, matching option C.
▶️ Answer/Explanation
Detailed solution:
A transverse wave is defined by vibrations occurring at $90^{\circ}$ (right angles) to the direction of energy transfer.
Common examples of transverse waves include electromagnetic radiation and water waves.
In contrast, sound waves are longitudinal, meaning their vibrations are parallel to the wave direction.
Row A is incorrect because sound is longitudinal; Rows C and D are incorrect because transverse vibrations are not parallel.
Therefore, Row B correctly identifies both the perpendicular nature of the vibrations and a valid example.
This aligns with the syllabus requirement to model water waves as transverse motions.
▶️ Answer/Explanation
Detailed solution:
Label $X$ points to a line representing a surface of constant phase, such as a crest, which is defined as a wavefront.
Label $Y$ indicates the shortest distance between two consecutive wavefronts (two successive crests), which defines the wavelength $\lambda$.
In this “view from above,” amplitude cannot be seen as it represents the vertical displacement from the rest position.
Therefore, $X$ is a wavefront and $Y$ is the wavelength, making Row B the correct choice.
▶️ Answer/Explanation
Detailed solution:
Images in a plane mirror undergo lateral inversion, meaning the left and right sides are interchanged.
In the reflected image, the minute hand points to $9$ (representing $45$ minutes) and the hour hand is between $4$ and $5$.
Applying lateral inversion, the minute hand at $9$ reflects to the $3$ position, which represents $15$ minutes.
The hour hand, appearing past the $4$ mark in the mirror, reflects to a position just past the $7$ mark.
Therefore, the actual time shown on the physical clock is $7:15$.
This confirms that Option C is the correct choice based on the laws of reflection.
▶️ Answer/Explanation
Detailed solution:
All angles in optics are measured between the light ray and the normal, which is the dashed line perpendicular to the surface.
The angle of reflection is the angle between the reflected ray and the normal in the first medium; in the diagram, this is identified as angle $1$.
The angle of refraction is the angle between the refracted ray and the normal in the second medium; in the diagram, this is identified as angle $4$.
Angles $2$ and $3$ are incorrect because they are measured from the ray to the glass surface (the interface) rather than the normal.
According to the law of reflection, the angle of incidence equals the angle of reflection ($i = r$).
Therefore, the correct row identifying the required angles is B.
▶️ Answer/Explanation
Detailed solution:
The loudness of a sound wave is directly related to its amplitude; as the amplitude increases, the sound becomes louder.
The pitch of a sound is determined by its frequency, where a higher frequency $f$ results in a higher-pitched sound.
Since the question states both the amplitude and frequency increase, both the loudness and the pitch must increase accordingly.
This relationship is consistent with the wave property where energy is proportional to $Amplitude^{2}$ and perceived tone depends on $f$.
Therefore, Row D correctly identifies that both characteristics will increase.
▶️ Answer/Explanation
Detailed solution:
The human range of audible frequencies is approximately $20\text{ Hz}$ to $20000\text{ Hz}$.
Ultrasound is defined as sound with a frequency higher than $20\text{ kHz}$ ($20000\text{ Hz}$).
Both audible sound and ultrasound are longitudinal waves that travel at the same speed in a given medium.
In air, this speed is approximately $330\text{ m/s}$ to $350\text{ m/s}$.
Option A is correct because it accurately identifies the human hearing range and the correct speed of the wave in air.
Other options are incorrect as they provide the wrong speed ($100\text{ m/s}$) or misdefine the frequency limits of ultrasound.
▶️ Answer/Explanation
Detailed solution:
Magnetic materials are classified by how easily they can be magnetised or demagnetised.
Soft iron is a “soft” magnetic material; it is easy to magnetise but loses its magnetism quickly, making it easy to demagnetise.
Steel is a “hard” magnetic material; it is more difficult to magnetise, but once magnetised, it retains it, making it hard to demagnetise.
This makes soft iron ideal for temporary magnets (like electromagnets) and steel ideal for permanent magnets.
Therefore, Row B correctly identifies these distinct physical properties for both materials.
▶️ Answer/Explanation
Detailed solution:
Electrostatic theory states that opposite charges attract while like charges repel.
Rod X is attracted to a negative rod, meaning X must possess an opposite (positive) charge.
Rod Y is repelled by the negative rod, meaning Y must possess a like (negative) charge.
Therefore, the charge on X is positive and the charge on Y is negative.
This corresponds exactly to the configuration presented in Row C.
▶️ Answer/Explanation
Detailed solution:
Electrical power $P$ is calculated using the formula $P = IV$.
For A: $P = 12\text{ V} \times 3.0\text{ A} = 36\text{ W}$.
For B: $P = 110\text{ V} \times 0.40\text{ A} = 44\text{ W}$.
For C: $P = (400 \times 10^{3}\text{ V}) \times (0.10 \times 10^{-3}\text{ A}) = 40\text{ W}$.
For D: $P = 240\text{ V} \times 0.20\text{ A} = 48\text{ W}$.
Comparing the results, the mains lamp (Option D) develops the greatest power at $48\text{ W}$.
▶️ Answer/Explanation
Detailed solution:
Double insulation means the appliance has two layers of insulation between the live internal parts and the user.
The outer casing is made of a non-conducting material (insulator), such as plastic, rather than metal.
Because the casing is an insulator, it cannot conduct electricity even if an internal fault occurs.
Consequently, the outer casing cannot become live, making an earth wire connection unnecessary.
A neutral wire is still required to complete the circuit, and a fuse is still needed to protect against $I^{2}R$ heating or excess current.
Thus, statement D is the only correct description of the safety benefit provided by double insulation.
▶️ Answer/Explanation
Detailed solution:
A magnetic field is a vector field that describes the magnetic influence on moving electric charges and magnetic materials.
By definition, it is a region of space surrounding a magnet or a current-carrying conductor where a magnetic pole will experience a force $F$.
While it affects magnetic materials like iron, it does not exert a force on all metals (e.g., aluminum or copper) or all general objects.
Electric charges only experience a magnetic force when they are in motion relative to the field, whereas magnetic poles are always affected.
Therefore, the most precise description is that it is a region where magnetic poles experience a force.
This aligns perfectly with Option C.
▶️ Answer/Explanation
Detailed solution:
Charging by friction occurs when two insulators are rubbed together, causing a transfer of surface particles.
In solids, protons and neutrons are bound tightly within the nucleus and cannot move between objects.
Only electrons, which carry a negative charge of approximately $-1.6 \times 10^{-19} \text{ C}$, are mobile enough to be transferred.
When the plastic rod becomes positively charged, it means it has lost some of its negative electrons to the rubbing material.
This creates an imbalance where the number of positive protons exceeds the remaining negative electrons.
Therefore, the only particles transferred during this charging process are electrons.
▶️ Answer/Explanation
Detailed solution:
The total e.m.f. of cells connected in series is the sum of their individual values: $E_{total} = 1.5\text{V} + 1.5\text{V} + 1.5\text{V} = 4.5\text{V}$.
For resistors in a series circuit, the combined resistance is the sum of the individual resistances: $R_{total} = R_{1} + R_{2}$.
Substituting the given values, the total resistance is $R_{total} = 20\Omega + 20\Omega = 40\Omega$.
Comparing these results to the table, Row D correctly identifies both values.
Therefore, the combined e.m.f. is $4.5\text{V}$ and the combined resistance is $40\Omega$.
▶️ Answer/Explanation
Detailed solution:
The turning effect (torque) on a coil in a magnetic field is directly proportional to the current I and the number of turns N.
Mathematically, the turning effect can be expressed by the relationship τ∝B⋅I⋅A⋅N, where B is the magnetic field strength and A is the area.
To ensure an increase in the turning effect, both variables I and N should be changed in a way that maximizes their product.
Increasing the current I provides more force per unit length of the wire according to F=BIl.
Increasing the number of turns N adds more lengths of wire, thereby multiplying the total force acting on the sides of the coil.
Therefore, only option D, which suggests increasing both the current and the number of turns, guaranteed an increase in the turning effect.
▶️ Answer/Explanation
Detailed solution:
The strength of a magnetic field around a conductor is directly proportional to the magnitude of the electric current ($B \propto I$).
Since the current increases from $3.0\text{ A}$ to $6.0\text{ A}$, the magnitude of the magnetic field strength increases.
The direction of the magnetic field is determined by the direction of the current, as shown by the Right-Hand Grip Rule.
By reversing the current direction, the circular magnetic field lines will now act in the opposite direction.
Therefore, the field both increases in strength and reverses its direction, making option C the correct choice.
▶️ Answer/Explanation
Detailed solution:
The total percentage of background radiation from all possible sources must equal $100\%$.
First, calculate the sum of the percentages for the four specific sources provided in the table:
$Total_{known} = 48\% + 13\% + 10\% + 11\% = 82\%$.
To find the percentage contributed by “all other sources,” subtract this known sum from the total:
$Percentage_{other} = 100\% – 82\% = 18\%$.
This calculation identifies that $18\%$ of the background radiation originates from sources not listed in the table.
Therefore, Option B is the correct answer.
▶️ Answer/Explanation
Detailed solution:
Radioactive decay involves the emission of radiation from an unstable nucleus to increase stability. In α-decay, the proton number decreases by 2. In β-decay, a neutron changes into a proton, increasing the proton number by 1. However, γ-radiation consists of high-energy electromagnetic waves rather than particles. Because it carries no charge and has no mass, the emission of a γ-ray does not change the proton number (Z) or the nucleon number (A) of the nucleus. Therefore, since the proton number remains unchanged, the event must be the emission of γ-radiation.
▶️ Answer/Explanation
Detailed solution:
An atom is initially neutral because the number of protons ($+1$ charge each) equals the number of electrons ($-1$ charge each).
When atoms lose electrons, they lose negative charge, resulting in a net positive charge since protons now outnumber electrons.
The resulting particle is a positively charged ion (specifically a cation).
Conversely, gaining electrons would create a negatively charged ion.
Therefore, the sentence is correctly completed as: “When they lose electrons, atoms form positively charged ions.”
This corresponds exactly to the sequence provided in Row C.
▶️ Answer/Explanation
Detailed solution:
The atomic number, often represented by the symbol $Z$, is defined as the number of protons found in the nucleus of an atom.
In this question, the isotope of krypton is explicitly stated to have an atomic number of $36$.
The mass number (or nucleon number, $A = 78$) represents the total sum of protons and neutrons, but does not change the identity or proton count of the element.
Since the atomic number is $36$, the number of protons must also be $36$.
This matches Option A.
▶️ Answer/Explanation
Detailed solution:
The Earth rotates on its tilted axis, completing one full rotation in approximately $24$ hours, which creates the cycle of day and night.
Simultaneously, the Earth travels in an elliptical path around the Sun, completing one full revolution or orbit in approximately $365$ days (one year).
The Moon, by contrast, takes approximately $1$ month to complete its orbit around the Earth.
Therefore, the correct time intervals for the Earth’s motions are $24$ hours for axial spin and $365$ days for solar orbit.
Matching these facts to the table, Row B provides the accurate duration for both astronomical events.
▶️ Answer/Explanation
Detailed solution:
Redshift occurs when the light from an object receding from the observer is stretched.
This stretching results in an increase in the observed wavelength $\lambda$ of the electromagnetic radiation.
Option A is incorrect because light from galaxies moving towards Earth would be blueshifted (decreased $\lambda$).
Option C is incorrect as the Big Bang Theory describes the expansion of the Universe itself, not just the Solar System.
Option D is factually incorrect regarding the timeline and rate of expansion to the current size.
Therefore, statement B is the only scientifically accurate definition of redshift provided.
▶️ Answer/Explanation
Detailed solution:
The Milky Way is classified as a galaxy, which is a massive system consisting of gas, dust, and billions of stars.
Our Solar System is merely a small part of the Milky Way, not the other way around as suggested in option B.
While we see many stars from the Milky Way in the night sky, we cannot see all of its billions of stars with the naked eye.
A comet’s path is a local orbital trajectory within the Solar System and is unrelated to the definition of a galaxy.
The diameter of the Milky Way is approximately $100000$ light-years, and it contains our Sun as one of its many stars.
Therefore, statement A is the only scientifically accurate description of the Milky Way’s nature.