1. (i) Medha wants to segregate biodegradable and non-biodegradable waste so that these can be properly and safely disposed of without causing any harm to environment and ecology. (ii) Medha is a conscientious student who believes that our environment must remain clean and non-polluted and all of us caRead more

    (i) Medha wants to segregate biodegradable and non-biodegradable waste so that these can be properly and safely disposed of without causing any harm to environment and ecology.
    (ii) Medha is a conscientious student who believes that our environment must remain clean and non-polluted and all of us can live healthy.
    (iii) Medha will use biodegradable waste to produce biogas or compost mannure.

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  2. When a circular coil of N tums is placed vertically in east-west direction and a current is passed through it, the magnetic field at the centre of coil points horizontally along north-south direction. The magnetic compass needle placed there was already pointing in north-south direction' Hence thereRead more

    When a circular coil of N tums is placed vertically in east-west direction and a current is passed through it, the magnetic field at the centre of coil points horizontally along north-south direction. The magnetic compass needle placed there was already pointing in north-south direction’ Hence there is no deflection shown by the magnetic needle’ When the coil is turned through 90° about a vertical axis, the coil is now in north-south direction and magnetic field due to current is along east-west direction horizontally. As a result the magnetic needle shows deflection. When the coil is further turned through 90° it again lies in east-west direction vertically and magnetic field due to current flow in the coil is along north-south horizontally. Hence, the magnetic needle remains in its equilibrium position and shows no deflection.

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  3. In multicellular organisms, the body size is large and diffusion pressure alone is not enough to carry food, exchange gases or remove wastes. If diffusion were to move oxygen in our body, it is estimated that it would take 3 years for a molecule of oxygen to get to our toes from our lungs. Thus, mulRead more

    In multicellular organisms, the body size is large and diffusion pressure alone is not enough to carry food, exchange gases or remove wastes. If diffusion were to move oxygen in our body, it is estimated that it would take 3 years for a molecule of oxygen to get to our toes from our lungs. Thus, multicellular organisms have developed various organs/organ systems for transportation of gases, wastes, food etc., like blood in animals or xylem and phloem in plants etc.

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  4. Double circulation occurs in humans. It refers to the passage of same blood twice through the heart. The right side receives deoxygenated blood whereas the left chambers of the heart pump oxygenated blood. There is no intermixing of oxygenated and deoxygenated blood. The oxygenated blood from lungsRead more

    Double circulation occurs in humans. It refers to the passage of same blood twice
    through the heart. The right side receives deoxygenated blood whereas the left chambers of the heart pump oxygenated blood. There is no intermixing of oxygenated and deoxygenated blood. The oxygenated blood from lungs comes to left auricle through pulmonary veins. Simultaneously, the deoxygenated blood comes to right auricle through two large veins Contraction of ventricles results in transfer of blood from them into lungs and various body parts. Precisely left ventricle on contraction sends oxygenated blood to body through the largest
    artery Aorta. While the right ventricle pumps the blood into lungs and for oxygenation through pulmonary artery. The separation of the right side and left side of the heart is useful so as to prevent oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body. This is useful in animals that have high energy needs, such as birds and mammals, Which constantly use the energy to maintain their body temperature.

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  5. Relation between oxidation and oxidising agent: Addition of oxygen or removal of hydrogen is called oxidation. The substance that brings about oxidation is called oxidising agent. Example: Fe₂O₃ + 2Al ⟶A1₂O₃ + 2Fe In this example, Fe₂O₃ has acted as oxidising agent and A1 has been oxidised.

    Relation between oxidation and oxidising agent:
    Addition of oxygen or removal of hydrogen is called oxidation.
    The substance that brings about oxidation is called oxidising agent.
    Example: Fe₂O₃ + 2Al ⟶A1₂O₃ + 2Fe
    In this example, Fe₂O₃ has acted as oxidising agent and A1 has been oxidised.

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