1. c) Excretion Kidneys are the paired organ that helps in maintaining the fluid electrolyte balance and acid base balance by the urine formation. Excretion is the process of removal of the feces or the metabolic waste from the body.

    c) Excretion

    Kidneys are the paired organ that helps in maintaining the fluid electrolyte balance and acid base balance by the urine formation. Excretion is the process of removal of the feces or the metabolic waste from the body.

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  2. Mendeleev’s periodic table 1. Elements are arranged in the increasing order of their atomic masses. 2. There are a total of 7 groups (columns) and 6 periods (rows). 3. Elements having similar properties were placed directly under one another. 4. The position of hydrogen could not be explained. ModerRead more

    Mendeleev’s periodic table

    1. Elements are arranged in the increasing order of their atomic masses.

    2. There are a total of 7 groups (columns) and 6 periods (rows).

    3. Elements having similar properties were placed directly under one another.

    4. The position of hydrogen could not be explained.

    Modern periodic table

    1. Elements are arranged in the increasing order of their atomic numbers.

    2. There are a total of 18 groups (columns) and 7 periods (rows).

    3. Elements having the same valence shell are present in the same period while elements having the same number of valence electrons are present in the same group.

    4. Hydrogen is placed above alkali metals.

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  3. The electronic configuration of elements with : Atomic number 12 = 2, 8, 2 Atomic number 19 = 2, 8, 8, 1 Atomic number 20 = 2, 8, 8, 2 Atomic number 21 = 2, 8, 9, 2 Atomic number 38 = 2, 8, 18, 8, 2 Elements with atomic number 12 i.e., magnesium (Mg) and 38 i.e., strontium (Sr) will have similar phyRead more

    The electronic configuration of elements with :
    Atomic number 12 = 2, 8, 2
    Atomic number 19 = 2, 8, 8, 1
    Atomic number 20 = 2, 8, 8, 2
    Atomic number 21 = 2, 8, 9, 2
    Atomic number 38 = 2, 8, 18, 8, 2
    Elements with atomic number 12 i.e., magnesium (Mg) and 38 i.e., strontium (Sr) will have similar physical and chemical properties as element with atomic numbers 20 i.e., calcium (Ca).

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  4. Modern periodic table is based on the atomic number and atomic number is directly related to the electronic configuration. One can find the group number and period number of an element on the basis of electronic configuration. For example, if an element has 1 or 2 electrons in its outermost shell, tRead more

    Modern periodic table is based on the atomic number and atomic number is directly related to the electronic configuration. One can find the group number and period number of an element on the basis of electronic configuration. For example, if an element has 1 or 2 electrons in its outermost shell, then it would belong to group 1 or group 2. And if it has 3 or more electrons in its outermost shell, then it would belong to group 10 4- the number of electrons in the outermost shell.

    All the alkali metals have one electron in their outermost shell, so they are placed in group 1. Thus, all the group 2 elements have 2 electrons in their outermost shell. In group 15 elements, there are 5 electrons in their outermost shell. Similarly, the number of shells in an element indicates its period number. For example, the atomic number of magnesium is 12 and its electronic configuration is 2, 8, 2. Thus it is an element of 3rd period.

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  5. Electronic configuration of nitrogen -2,5 Electronic configuration of phosphorus = 2, 8, 5 Nitrogen will be more electronegative because outermost shell is nearer to nucleus and therefore nucleus will attract electrons more strongly. In a group of the periodic table, electron attracting tendency decRead more

    Electronic configuration of nitrogen -2,5
    Electronic configuration of phosphorus = 2, 8, 5
    Nitrogen will be more electronegative because outermost shell is nearer to nucleus and therefore nucleus will attract electrons more strongly. In a group of the periodic table, electron attracting tendency decreases as we move from top to bottom.

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