Learn 80 questions from K-TET III - December 2025 - Part III (Physical Science)

K-TET III - December 2025 - Part III (Physical Science) Questions

• An Ellingham diagram is a graph that shows the temperature dependence of the stability of compounds. In metallurgy, it is primarily used to predict the ease of reduction of metal oxides and sulfides.

Gibbs free energy in connection with metallurgy

• Light rays coming from a very distant object, such as the Sun, are considered parallel to the principal axis of the lens.
•  By definition, a convex lens is a converging lens that brings these parallel rays of light to a single point after refraction. This point is known as the principal focus, or simply the focus, of the lens.

• Fluorine is the first member of Group 17 (the halogens), 
• It is the most electronegative element in the entire periodic table (4.0 on the Pauling scale). This makes it very greedy for electrons and significantly affects its bonding characteristics.

• The activated complex (also known as the transition state) is a temporary, unstable arrangement of atoms that forms at the peak of the energy barrier during a chemical reaction.
• To form an activated complex, reactants must absorb energy (Activation Energy, Therefore, the complex always has higher energy than the starting reactants.
• Because it is at a high-energy state, the activated complex is extremely unstable and has a very short life span (often on the scale of femtoseconds).
• Once at the transition state, the complex can either "fall" forward to become products or "fall" backward to revert to the original reactants.

Activated complexes possess higher energy than the reactants.

Activated complexes possess lower energy than the products.

They can revert back to reactants or proceed forward to form products.

• When light enters a medium like glass, it slows down compared to its speed in a vacuum. However, not all colors slow down by the same amount. This is due to a phenomenon called dispersion.
• In any medium like glass, the speed of light is dependent on its wavelength. Red light has the longest wavelength among the colors of the visible spectrum (VIBGYOR), while violet light has the shortest.

• The problem states the element belongs to the 3rd period. Therefore, the principal quantum number for its outermost shell is n = 3
• We are given that the (n + l) value of the outermost subshell is 4
• .Using the value of n we just identified:3 + l = 4
• l = 4 - 3
• l = 1is the p subshell.
•  the outermost subshell is 3p.

• Total Internal Reflection is a specific optical phenomenon that can only happen when two specific conditions are met:
• Density Requirement: Light must travel from a denser medium (higher refractive index) to a rarer medium (lower refractive index).
• Angle Requirement: The angle of incidence must be greater than the critical angle for that pair of media.

• A stationary wave is formed when two progressive waves of the same frequency and amplitude travel in opposite directions and superimpose on each other.
• Energy Confinement: In a stationary wave, the energy is "trapped" or confined between specific points called nodes (points of zero displacement). The energy oscillates back and forth within these segments but does not move forward through the medium.
• Nodes and Antinodes: At the nodes, the displacement is always zero, effectively acting as a barrier that prevents the flow of energy to the next segment.
•  Progressive Waves: By definition, these are waves that "progress" through a medium, transferring energy from one point to another without the permanent displacement of the particles.
• Transverse Waves: This describes the direction of particle oscillation (perpendicular to wave travel). Most transverse waves (like those on a plucked guitar string or light) are progressive and carry energy
•  Electromagnetic Waves: These waves (like sunlight or X-rays) are the primary way energy is transferred through the vacuum of space. They carry massive amounts of energy.

• Plasma is an ionized gas and is often referred to as the fourth state of matter. It is the most abundant state of matter in the universe because it makes up stars and large interstellar bodies like nebulae.
•  On Earth, examples of plasma include lightning and the contents of fluorescent light bulbs.

• Salt hydrolysis is the reaction of the ions of a salt with water to produce an acidic or basic solution. The salt must be formed from a weak acid, a weak base, or both.

<h3 style="color: rgb(255,255,255);">Oganesson (Og)</h3><ul style="color: rgb(255,255,255);"><li>Oganesson is a synthetic chemical element with the symbol Og and atomic number 118.</li><li>It is the element with the highest atomic number (number of protons) and consequently the highest mass number (total number of protons and neutrons) currently known.</li><li>As of its discovery, it was the last element in the 7th period of the periodic table.</li><li>It is a transactinide element and belongs to Group 18, the noble gases. However, due to relativistic effects, its chemical properties are predicted to differ significantly from lighter noble gases, and it may not be a gas at standard conditions.</li><li>The element was first synthesized in 2002 by a joint team of Russian and American scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia.</li><li>It was officially named Oganesson on November 28, 2016, in honor of the Russian nuclear physicist Yuri Oganessian, who made significant contributions to the discovery of superheavy elements.</li><li>Oganesson is highly radioactive, and all its known isotopes have very short half-lives, decaying within milliseconds.</li><li>Due to its extreme instability and the minute quantities produced, Oganesson has no known practical applications.</li><li>The synthesis of Oganesson involves bombarding Californium-249 with Calcium-48 ions.</li><li>It is considered a placeholder in the periodic table, and theoretical studies continue to explore the properties of elements beyond 118.</li></ul>

Photochemical reaction and Endothermic reaction

Photochemical Exothermic reaction reaction &Exothermic reaction

• To make a p-type semiconductor using a Germanium (Ge) crystal, it must be doped with an impurity atom whose valency is 3.

• When an object falls freely in a vacuum, the only force acting upon it is gravity. Because there is no air resistance (drag) in a vacuum to oppose the motion, the object continues to speed up at a constant rate.
• Acceleration is the rate of change of velocity. Since the force of gravity is constant near the Earth's surface, the object's velocity increases by the same amount (9.8 m/s) every second.

• Lenz's law states that the direction of the induced current in a conductor is such that it opposes the change in magnetic flux that caused it.
•  This opposition requires external work to be done to maintain the change in flux (e.g., moving a magnet), and this work is converted into the electrical energy of the induced current.
•  Therefore, Lenz's law is a direct application of the principle of conservation of energy.

• Orthophosphoric acid has the chemical formula NaH3PO4
• A salt of this acid is formed when one or more of its acidic hydrogen atoms are replaced by a cation, such as sodium Na+

• Dynamic lift, as observed in an airplane wing (aerofoil) or the Magnus effect in a spinning ball, relies on the difference in fluid velocity across the object. 
• According to Bernoulli's theorem, regions of higher fluid velocity correspond to lower pressure, and regions of lower velocity correspond to higher pressure. This pressure difference generates a net force, the dynamic lift.

• To find the hybridization of a central atom, we calculate its Steric Number (SN), which is the sum of the number of bonded atoms and the number of lone pairs on the central atom.
•  Phosphorus (P), which belongs to Group 15 and has 5 valence electrons.
• It is bonded to 5 Chlorine atoms.
• All 5 electrons are used in bonding, so there are 0 lone pairs.
• Steric Number: 5  (bonds) + 0  (lone pairs)}= 5
• A Steric Number of 5 corresponds to sp^3d hybridization.
• This results in a trigonal bipyramidal geometry.

• While a transformer does involve electromagnetic induction broadly, the specific mechanism that allows it to transfer energy from one coil to another without a physical connection is mutual induction.

• In a capacitor, energy is not stored "inside" the physical material of the plates or on a single charge; rather, it is stored in the electric field that exists in the space (or dielectric) between the plates.

Momentum and kinetic energy are conserved

• In chemical kinetics, the rate of reaction refers to how fast a reaction proceeds. 
• While several factors can change the speed of the particles or the frequency of their collisions, the thermodynamic stability of the products versus the reactants does not dictate the speed.
• The Heat of Reaction is a thermodynamic property. it tells us whether a reaction is exothermic (releases heat) or endothermic (absorbs heat). It only describes the difference in energy between the starting materials and the final products.

•  Particles cannot be separated by filtration: This statement is true for both true solutions and colloids. The particles in both are small enough to pass through a filter paper and cannot be separated by simple filtration. 
• Particles do not settle down when kept undisturbed: This statement is true for both true solutions and colloids. Both are stable, and their particles do not settle down over time when left undisturbed. In contrast, a suspension's particles would settle.

 Particles cannot be separated by filtration.

 Path of the light beam is visible, on passing an intense beam of light.

 Particles do not settle down when kept undisturbed.

• Dmitri Mendeleev, the father of the periodic table, formulated the Periodic Law in 1869, which stated that the physical and chemical properties of elements are a periodic function of their atomic weights (masses).

the presence of very strong Vander Waals' forces

• A colloid is a heterogeneous mixture in which the particles are larger than those in a solution but smaller than those in a suspension. Colloidal particles are dispersed uniformly throughout another substance and do not settle over time.

• The activity described involves measuring, recording observations, and inferring, which are all active processes or skills used in scientific inquiry. 
• The process aspect of science focuses on the methods and skills scientists use to investigate the world, rather than just the final facts or knowledge produced.

• Guided discovery learning is a teaching strategy where the instructor facilitates students to discover principles and relationships for themselves, a concept most closely associated with Jerome Bruner's theories on cognitive development and constructivism.

• Jerome Bruner advocated for the spiral curriculum approach, where fundamental concepts are introduced early and revisited repeatedly throughout a student's education, increasing in complexity and depth with each encounter. 
• This method is based on the idea that any subject can be taught effectively in some intellectually honest form to any child at any stage of development.

• Inductive reasoning is commonly used in scientific discovery to form hypotheses.
•  It involves moving from specific observations to broad generalizations or hypotheses. In contrast, deductive reasoning starts with a general premise and logically leads to a specific conclusion, which is often used later in the scientific method for testing hypotheses.

• This family of models focuses on the ways people handle stimuli from the environment, organize data, sense problems, and generate solutions. It is deeply rooted in cognitive psychology.

• Primary Goal: To enhance the student’s ability to think, process information, and acquire knowledge.

• Key Focus: Intellectual development, logical reasoning, and memory.

• Examples: Bruner’s Concept Attainment Model, Ausubel’s Advance Organizer Model, and Suchman’s Inquiry Training Model.

• An integrated approach to teaching science moves beyond teaching individual subjects in isolation. 
• It is more effective for a holistic understanding because it helps learners connect concepts across different scientific disciplines and apply them to real-life situations. This method encourages deeper comprehension and critical thinking, rather than simple memorization of isolated facts

Focuses on memorization of scientific facts

Teach each science discipline as completely independent

Help learners relate concepts across different branches of Science and real life

Limits learning to text-book based knowledge

• Signal learning, the lowest level in Gagné's hierarchy of learning, involves learning to make a general, diffuse emotional response to a signal or stimulus
• . This is based on classical conditioning, similar to Pavlov's experiments where a subject learns an involuntary response to a new stimulus.

• n-service training, workshops, and seminars are all forms of professional development activities that a teacher might attend to improve their skills and knowledge.
•  These are typically external or group activities aimed at ongoing learning. Lesson planning, however, is a fundamental and ongoing part of a teacher's daily responsibilities within their role, rather than a separate professional development activity. 
• It is a core pedagogical skill used to prepare for teaching a specific class.

Checklist  -recording presence or absence of traits

Rating scale-  measuring degree of performance

Portfolio - continuous assessment of student work

Achievement test-  Assessing practical skills

• A learner-centered approach focuses on the student's active engagement and self-directed learning. 
• Activities, experiments, thought-provoking questions, and opportunities for self-evaluation are all features that encourage student participation and independent learning. 
• The absence of review exercises would hinder a student's ability to practice and consolidate their understanding, which contradicts the principles of a learner-centered textbook. 
• The other options are all positive features that support active learning.

• A teacher who consistently uses visual materials to promote teamwork and collaboration is demonstrating leadership. Leadership involves guiding, motivating, and influencing others towards a common goal, which in this case is teamwork and collaboration in the classroom. While communication is a part of leadership, the overall act of fostering a collaborative environment through specific strategies falls under the broader umbrella of leadership competency.
•  Classroom management involves maintaining order and organization, and content mastery is about knowledge of the subject matter, neither of which directly addresses promoting teamwork and collaboration.

• The basic science process skills are observing, classifying, communicating, measuring, inferring, and predicting. Hypothesizing is considered an integrated science process skill, which involves using several basic skills simultaneously, rather than a basic one itself.

• M. Gagné is an American educational psychologist best known for his "Conditions of Learning" theory, which outlines a hierarchy of eight types of learning outcomes, ranging from simple signal learning to complex problem-solving.

• While audio-visual (AV) aids might incidentally help with classroom management or save a teacher from drawing complex diagrams on a chalkboard, those are secondary benefits. Their pedagogical "soul" lies in how they interact with the human brain.

Enhance understanding through multi sensory learning

• A science fair promotes science learning beyond the classroom instruction because it involves hands-on projects, experimentation, and research that typically take place outside of regular class time. 
• Students engage in independent inquiry, applying scientific principles to real-world problems or phenomena, which goes beyond traditional methods like rote memorization, textbook exercises, or the "chalk and talk" method, all of which are generally confined to the classroom setting.

• An interdisciplinary approach to teaching involves integrating concepts and methods from multiple academic disciplines to examine a central theme or topic.
•  In this case, climate change is the central topic, and the teacher is drawing upon science, geography, social studies, and economics to provide a holistic understanding. This contrasts with a discipline-based approach, which would focus solely on the content and methods of a single subject.

• This concept is a cornerstone of Lev Vygotsky’s sociocultural theory of cognitive development. It identifies the "sweet spot" of learning where a student is challenged enough to grow but supported enough to succeed.

• The activity described involves students applying higher-order thinking skills. "Planning" and "conducting" a project to "address" a real-world problem requires them to evaluate various solutions and create a viable plan and outcome.
•  This aligns with the top levels of Bloom's Taxonomy, specifically 'evaluating' (making judgments about methods and ideas) and 'creating' (producing a new plan or solution).
•  The other options represent lower-order thinking skills like simple recall, recognition, analysis, and synthesis, which are components of the process but not the overall promoted level of learning for the entire project.

• Behaviorists define learning strictly as a measurable change in how an organism acts. If there is no visible change in performance (e.g., a student correctly balancing a chemical equation), a behaviorist would argue that learning has not yet occurred.
• This is the core of "Operant Conditioning." Positive reinforcement (rewards/praise) or negative reinforcement (removal of a stimulus) is used to increase the likelihood that a desired behavior will be repeated.
• This is an assumption of Cognitivism or Constructivism (like Piaget). These theories focus on internal mental maps and how we reorganize information in our heads. Behaviorists ignore these internal "restructurings."
• This aligns more with Humanistic or Social-Emotional Learning (SEL) approaches. Behaviorists view emotions as subjective and unobservable, therefore they are not the primary focus of their teaching methods.

 Learning is a change in observable behaviour

 Emotions are the central focus of learning

Learning occurs mainly through cognitive restructuring

• The first step in any effective problem-solving strategy is to clearly identify and define the problem. 
• This ensures a clear understanding of what needs to be addressed before moving on to collecting data, implementing solutions, or evaluating outcomes. The subsequent steps typically involve data collection, developing possible solutions, selecting and implementing the best solution, and finally, evaluation.

Evaluating the effectiveness of the solution

Routine activities and exercises to assess learning

Evaluation of all aspects of student's development

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