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प्रश्न
State the modern periodic law for classification of elements. How many (i) groups and (ii) periods are there in the modern periodic table?
उत्तर
Modern periodic law:
“Properties of elements are a periodic function of their atomic number”.
(i) There are 18 groups (group 1 − group 18) and
(ii) 7 periods in the modern periodic table.
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