NCERT Class 9 Science Solutions: The Fundamental Unit of Life Question: How do substances like CO2 and water move in and out of the cell? Discuss. Concept in a Minute: Cell membrane structure (fluid mosaic model), permeability (semi-permeable), and transport mechanisms (diffusion, osmosis, active transport). Explanation: Substances like CO2 and water move across the cell membrane […]

NCERT Class 9 Science Solutions: Structure of the Atom Question: Which one of the following is a correct electronic configuration of sodium? A. 2, 8 B. 8, 2, 1 C. 2, 1, 8 D. 2, 8, 1 Concept in a Minute: Electronic configuration describes the arrangement of electrons in different energy shells or orbitals of

NCERT Class 9 Science Solutions: Sound Question: Why are the ceilings of concert halls curved? Concept in a Minute: Sound reflection, specifically the principle of reflection where the angle of incidence equals the angle of reflection. Echoes and reverberation are also relevant. Explanation: The ceilings of concert halls are curved to ensure that sound waves

NCERT Class 9 Science Solutions: Motion Question: An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s? Concept in a Minute: Circular motion, distance, displacement, speed, time, unit conversion. Distance is the

NCERT Class 9 Science Solutions: Matter in Our Surroundings Question: Why is ice at 273 K more effective in cooling than water at the same temperature? Concept in a Minute: The key concept here is the difference between sensible heat and latent heat. Sensible heat is the heat absorbed or released by a substance that

NCERT Class 9 Science Solutions: Is Matter Around Us Pure Question: Classify the following as chemical or physical change: Burning of paper and wood A. Chemical change B. Physical change Concept in a Minute: Physical change: A change in which the form or appearance of a substance changes, but its chemical composition remains the same.

NCERT Class 9 Science Solutions: Improvement in Food Resources Question: For increasing production, what is common in poultry, fisheries and bee-keeping? Concept in a Minute: Animal Husbandry: The management and breeding of domestic animals, especially livestock. This includes practices aimed at improving the yield of products like meat, milk, eggs, wool, honey, and fish. Key

NCERT Class 9 Science Solutions: Gravitation Question: What is the importance of the universal law of gravitation? Concept in a Minute: The universal law of gravitation describes the force of attraction between any two objects with mass. It’s crucial for understanding celestial motion, Earth’s gravity, and tides. Explanation: The importance of the universal law of

NCERT Class 9 Science Solutions: Force and Laws of Motion Question: A batsman hits a cricket ball which then rolls on a level ground. After covering a short distance, the ball comes to rest. The ball slows to a stop because ______. A. the batsman did not hit the ball hard enough. B. velocity is

NCERT Class 9 Science Solutions: Atoms and Molecules Question: Calculate the molecular mass of CH4. Concept in a Minute: Molecular mass is the sum of the atomic masses of all the atoms in a molecule. Atomic mass is the mass of an atom of a chemical element, usually expressed in atomic mass units (amu). To