NCERT books are always considered to be the best source to reach the depth of every topic given in a subject. In school exams or board exams, problems are asked in different formats like very short answer type, short answer type and long answer type questions which are generally asked on the basis of topics explained in the NCERT books. However, these questions are designed in a twisted way so as to test the basic concepts of students. To break these problems students are recommended to read the NCERT Books thoroughly. These books help you in understanding your topics well and are ideal for thorough and comprehensive studying to develop a clear concept.
Moreover, the problems given in the NCERT books are a good source of practice to familiarise with different types of questions and be efficient at solving them correctly.
To help students find the right approach to all the questions given in CBSE Class 11 Chemistry NCERT book we are providing here the NCERT solutions explained by subject matter experts.
In this article we are providing the NCERT solutions for Class 11 Chemistry chapter 9, Hydrogen. These solutions will make it easy for you to prepare easily and effectively for the annual exams.
Main topics discussed in Class 11 Chemistry chapter- Hydrogen are:
- Position of hydrogen in the periodic table
- Dihydrogen, h2
- Isotopes of hydrogen
- Preparation of dihydrogen, h2
- Properties of dihydrogen
- Uses of dihydrogen
- Hydrides and their types
- Water and its physical/chemical properties
- Structure of water and ice
- Hard and soft water
- Hydrogen peroxide (H2O2), its preparation, properties, storage and uses
- Heavy water, D2O
- Dihydrogen as a fuel.
Some of the questions and their solutions from NCERT Solutions for Class 11: Hydrogen, are as follows:
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 recombines 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.
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