Thursday 2 July 2020

Chemistry For HSC Part 2 - Chapter No.2 - Scientific Reasons

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Chapter No.2
Hydrogen
Scientific Reasons


Q.1: Why Ionic hydrides are true hydrides?
Ans. Hydrides are binary compound of hydrogen. Ionic hydrides are only one in which hydrogen has negative charge (H).

Q.2: Why position of hydrogen in modern periodic table is difficult to choose?
Ans. The position of hydrogen in modern periodic table is a puzzle because of the limitation of first electrons shell causing controversial properties of loosing, gaining and sharing of electrons. Due to the fact, its position is not definite. However, in most periodic tables, it is placed at the top of the periodic table.



Q.3: Why Be and Mg do not form Ionic hydrides?
Ans. Because we know that Be and Mg are smaller in size they have large charge density and has intermediate properties of ionic and covalent. Due to this reason their molecule gets polymerized and do not form fully ionic hydrides. These have partially ionic and partially covalent properties.

Q.4: Why nascent or atomic hydrogen is more reactive than molecular hydrogen?
Ans. Nascent hydrogen (newly born) occurs in atomic state has greater energy and needs to be stabilized by decreasing energy. That's why it remains ready to react with those substance which are not reacted by molecular hydrogen (already stabled).

Q.5: Why heavy water is heavy?
Ans. Heavy water has heavier isotope of hydrogen i.e. Deuterium that's why it is called as heavy water. It has formula D2O.

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