Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
Physics Key Terms
| Term | Definition |
|---|---|
| Distance | Total path length covered by an object (scalar) |
| Displacement | Shortest distance from initial to final position with direction (vector) |
| Speed | Distance covered per unit time. SI unit: m/s (scalar) |
| Velocity | Displacement per unit time with direction. SI unit: m/s (vector) |
| Acceleration | Rate of change of velocity. a = (v−u)/t. SI unit: m/s² |
| Uniform Motion | Equal distances in equal intervals of time |
| Non-uniform Motion | Unequal distances in equal intervals of time |
| Retardation | Negative acceleration — deceleration |
| Least Count | Smallest measurement an instrument can reliably take |
| Vernier Calliper | Instrument measuring lengths up to 0.1 mm accuracy |
| Screw Gauge | Instrument measuring diameters up to 0.01 mm accuracy |
| Significant Figures | All certain digits + one uncertain digit in a measurement |
| Pressure | Force per unit area. P = F/A. SI unit: Pascal (Pa) |
| Pascal's Law | Pressure applied at one point of an enclosed fluid is transmitted equally in all directions |
| Buoyancy | Upward force exerted by a fluid on a submerged or floating object |
| Archimedes' Principle | When an object is submerged in a fluid, the buoyant force equals the weight of fluid displaced |
| Frequency | Number of vibrations per second. SI unit: Hz |
| Amplitude | Maximum displacement from mean position |
| Wavelength | Distance between two successive crests or troughs |
| Reverberation | Persistence of sound due to multiple reflections |
| Echo | Reflected sound heard distinctly at least 0.1 s after original |
Chemistry Key Terms
| Term | Definition |
|---|---|
| Matter | Anything that has mass and occupies space |
| Element | Pure substance that cannot be broken into simpler substances by chemical means |
| Compound | Pure substance formed by chemical combination of two or more elements in fixed ratio |
| Mixture | Combination of two or more substances in variable ratio (no chemical bond) |
| Evaporation | Surface phenomenon — liquid to vapour below boiling point |
| Sublimation | Solid to gas directly (and reverse: deposition) |
| Latent Heat | Heat absorbed/released during change of state without temperature change |
| Atom | Smallest particle of an element that takes part in chemical reactions |
| Electron | Negatively charged subatomic particle; mass ≈ 9.1 × 10⁻³¹ kg |
| Proton | Positively charged subatomic particle; mass ≈ 1.67 × 10⁻²⁷ kg |
| Neutron | Neutral subatomic particle; mass ≈ same as proton |
| Atomic Number | Number of protons in the nucleus of an atom |
| Mass Number | Total number of protons + neutrons in the nucleus |
| Isotopes | Atoms of the same element with same atomic number but different mass numbers |
| Isobars | Atoms of different elements with same mass number but different atomic numbers |
| Valency | Combining capacity of an atom — number of electrons gained, lost, or shared |
| Solution | Homogeneous mixture of solute dissolved in solvent |
| Solubility | Maximum amount of solute that dissolves in a given amount of solvent at a given temperature |
| Allotrope | Different structural forms of the same element (e.g., diamond and graphite — both carbon) |
| Periodic Table | Tabular arrangement of elements in increasing order of atomic number |
Biology Key Terms
| Term | Definition |
|---|---|
| Photosynthesis | Process by which green plants make food using sunlight, CO₂, and H₂O, releasing O₂ |
| Chlorophyll | Green pigment in plants that absorbs light energy for photosynthesis |
| Autotrophic | Mode of nutrition where organisms make their own food (e.g., plants) |
| Heterotrophic | Mode of nutrition where organisms depend on other organisms for food |
| Balanced Diet | Diet providing all nutrients in correct proportions for health |
| Deficiency Disease | Disease caused by lack of a specific nutrient |
| Neuron | Basic structural and functional unit of the nervous system |
| Central Nervous System | Brain + Spinal cord |
| Peripheral Nervous System | All nerves outside the brain and spinal cord |
| Reflex Action | Automatic, involuntary response to a stimulus without conscious brain involvement |
| Reflex Arc | Pathway of nerve impulse in a reflex action: receptor → sensory nerve → CNS → motor nerve → effector |
| Synapse | Junction/gap between two neurons where nerve impulse passes by chemical transmission |
| Axon | Long fibre carrying nerve impulse away from the cell body |
| Dendrite | Short branching extensions of neuron that receive signals |
| Cerebrum | Largest part of brain; controls thinking, memory, voluntary movement |
| Cerebellum | Controls balance, coordination, and fine motor movements |
| Medulla Oblongata | Controls automatic vital functions — breathing, heartbeat |
| Vertebrate | Animal with a backbone (Phylum Chordata) |
| Invertebrate | Animal without a backbone |
| Thallophyta | Simplest plant group — no differentiated root, stem, leaf (e.g., algae) |
Frequently Asked Questions
Aim to memorise 80-100 key definitions across all chapters. 1-mark questions are almost entirely definition-based. This bank covers the highest-priority terms.