1. (a) Middle lamella is made up of calcium pectate. https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-5/

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  2. (d) Chromosomes are made up of DNA and proteins. https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-5/

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  3. (d) Rutherford model only established that the nucleus is positively charged. https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-4/

    (d) Rutherford model only established that the nucleus is positively charged.

    https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-4/

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  4. (d) We use valency of the element to determine the molecular formula of a compound. The valencies are crossed to obtain the formula. https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-3/

    (d) We use valency of the element to determine the molecular formula of a compound. The valencies are crossed to obtain the formula.

    https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-3/

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  5. (a) Sodium and magnesium both contain 12 neutrons each. https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-4/

    (a) Sodium and magnesium both contain 12 neutrons each.

    https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-4/

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