Question

how many periodic laws are there

Answer 1

there are two periodic laws

classic periodic law according to this law the elements in the periodic table periodic function of their masses and

modern periodic law according to this law the elements of the periodic table are periodic function of their atomic numbers.

Answer 2

Heya!

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The Periodic Law states that physical and chemical properties of elements reoccur after regular intervals when they are arranged in increasing order of their atomic numbers.

Mendeleev's periodic law states that physical and chemical properties reoccur after intervals of time when they are arranged in increasing order of their atomic masses.

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Hope it helps...!!!