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Hydrogen: CBSE Class 11 NCERT Solution

Aug 4, 2015 11:30 IST

    Find the CBSE Class 11 Chemistry NCERT Solution for the Chapter- 9, Hydrogen. It has been framed keeping the Students' perspective in mind. This will help the Students with easy and simple understanding of the concept and technique employed in solving as per the CBSE Marking Scheme.

    To get the Complete NCERT Solution, Click Here

    Few Sample Question from this Chapter are given below:

    Q. Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

    Ans. The electronic configuration of hydrogen is 1s1. It has only one electron in its valence shell. It can either lose its only valence electron to behave like alkali metals or can gain one electron to behave like the halogens.

    Hydrogen atom resembles with alkali metals as:

    (1) It has only one electron in the valence shell like the alkali metals.

    (2) Like alkali metals, it forms oxides, halides and sulphides.

    Hydrogen atom resembles with halogens as:

    (1) Like halogens, it requires only one electron to achieve the nearest noble gas configuration.

    (2) Just like the halogens, hydrogen has a very high value of ionisation enthalpy.

    Therefore on the basis of above properties, hydrogen may be placed in the group-I of alkali metals or group-17 of halogens. However, besides the resemblance with alkali metals and halogens, hydrogen possesses some unique characteristics, which make it different from both alkali metals and halogens due to which it is best placed separately in the Periodic Table.

    Q. Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?

    Ans. Hydrogen atom has only one electron in its valence shell. So, to achieve the stable noble gas configuration of helium, it requires only one electron. For this it shares its one electron with another hydrogen atom to form a stable diatomic molecule.

    Q. Discuss the consequences of high enthalpy of H–H bond in terms of chemical reactivity of dihydrogen.

    Ans. The high enthalpy of H–H bond makes it a unreactive gas at room temperature. However at high temperature or in the presence of catalyst it combines with metals and nonmetals to form the respective metal hydrides.

    Q. How do you expect the metallic hydrides to be useful for hydrogen storage? Explain.

    Ans. In some the transition metal hydrides, hydrogen is adsorbed as H-atoms. As more of the hydrogen atoms are absorbed, the metal lattice expands and becomes a little unstable. Hence, these metal hydrides decompose even on slight heating to give out hydrogen gas. Thus transition metals can be used as the store house of hydrogen that can then be used for various industrial purpopses.

    Q. How does the atomic hydrogen or oxy-hydrogen torch function for cutting and welding purposes? Explain.

    Ans. Atomic hydrogen or oxy-hydrogen torch involves the formation of atomic hydrogen atoms that are produced by dissociation of dihydrogen with the help of an electric arc. The atomic hydrogen so produced immediately recombine to form molecular hydrogen with the liberation of tremendous amount of heat which is used for cutting and welding purpose in the form of atomic hydrogen or oxy-hydrogen torches.

    To get the Complete NCERT Solution, Click Here

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