General Science - CBT 1
What the domain tests
CBT 1 General Science is NCERT Class 9–10 level physics, chemistry and biology, tested as direct factual recall plus one-step numericals. Physics: motion, force, gravitation, work-energy, sound, light, electricity and magnetism. Chemistry: matter, atoms and molecules, acids-bases-salts, metals, carbon compounds, periodic trends. Biology: cell, tissues, nutrition, respiration, transport, reproduction, heredity, and human diseases.
Must-know facts
- SI units: force newton, pressure pascal, work joule, power watt, charge coulomb.
- Speed of sound is highest in solids, lowest in gases; it is about 343 m/s in air at room temperature.
- pH below 7 is acidic, above 7 basic; litmus turns red in acid, blue in base.
- Blue vitriol is CuSO₄·5H₂O; lime water turns milky with CO₂ due to CaCO₃.
- Deficiency: vitamin C → scurvy, vitamin D → rickets, iodine → goitre, iron → anaemia.
- Mitochondria is the powerhouse; ribosomes synthesise protein; chlorophyll absorbs mainly blue and red light.
Worked example
A 10 kg body accelerates at 3 m/s². Find the force. Using F = ma gives F = 10 × 3 = 30 N. If the same force acted on a 6 kg body, acceleration would be 30/6 = 5 m/s² - showing that for constant force, acceleration is inversely proportional to mass.
Traps that cost marks
Using weight (mg) where mass is asked. Confusing reflection (bouncing off a surface) with refraction (bending while changing medium). Mixing up arteries carrying blood away from the heart with veins carrying it back. And forgetting that sound needs a medium, so it cannot travel through a vacuum.