Answer:
(a) FALSE
(b) FALSE
(c) TRUE
(d) FALSE
Explanation:
Ionization energy refers to the energy needed for removal of a valence electron present in valence shell of a gaseous atom.
(a) <u>The value of ionization energy of an atom is always</u><u> positive</u>. This is because energy has to be always supplied or provided to a gaseous atom for the removal of the valence electron.
<em><u>Therefore, the statement (A) is</u></em><em><u> false</u></em>
(b) The ionization energy of an atom <u>increases across a period</u> i.e. from left to right. This is because the <u>effective nuclear charge that is experienced by the valence electron increases</u> from left to right in the periodic table, as the atomic number increases.
So, more energy is required to remove the valence electron of fluorine as compared to oxygen.
<u>Therefore, the </u><u>ionization energy of fluorine is greater than oxygen</u><u>.</u>
<em><u>Therefore, the statement (B) is</u></em><em><u> false</u></em>
(c) <u>First ionization energy</u> is energy needed for removal of first electron present in valence shell of a neutral atom. Whereas, <u>second ionization energy</u> is the energy needed for removal of second electron present in valence shell of a monovalent cation
The second ionization energy of an atom is always greater than the first ionization energy. This is because removing<u> an electron from a positively charged species, requires more energy.</u>
<em><u>Therefore, the statement (C) is</u></em><em><u> true</u></em>
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(d) <u>The third ionization energy </u>refers to the energy needed to remove the third electron from a divalent cation.
<em><u>Therefore, the statement (D) is</u></em><em><u> false</u></em>
molecules. Hence, it is a pure substance.