(a)What do you understand by the term variable valency?Name two elements having [2]
variable valency.
(b)Explain the formation of bondin (i)Hydrogen molecule,(ii)Oxygen molecule,and [3]
(iii)Nitrogen molecule.
(c)Explain with an example atomic number and atomic mass. [3]
(d)Define isotopes.State the possible isotopes of hydrogen atom.
Answers
Answer:
1 Some elements differ in their capacity to combine with other elements depending on the nature of the reaction; this property is called variable valency. For example, Iron (Fe) can have a valency of both 2 and 3.
2 Hydrogen bonding occurs only in molecules where hydrogen is covalently bonded to one of three elements: fluorine, oxygen, or nitrogen. These three elements are so electronegative that they withdraw the majority of the electron density in the covalent bond with hydrogen, leaving the H atom very electron-deficient
3 Mass number is the number of protons and neutrons in the nucleus taken together. For example, mass number of sodium is 23 g/mol. iii) Isotopes are elements with the same atomic number but different mass numbers. Example, hydrogen has 3 isotopes - protium (1H1), deuterium (2H1) and tritium (3H1).
4 Hydrogen has three main isotopes; protium (1H), deuterium (2H) and tritium (3H). These isotopes form naturally in nature. Protium and deuterium are stable. Tritium is radioactive and has a half-life of about 12 years. ... The main isotopes of hydrogen are unique because they are the only isotopes that have a name.
Explanation:
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