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The Brainliest Answer!
2014-12-11T20:43:07+05:30
Periods-they are the horizontal row of periodic table 
there are 7 periods in the periodic table...
:)

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the horiperiods-they are the horizontal row of periodic table
there are 7 periods in the periodic table...
:)
  • Rio
  • Ambitious
2014-12-11T20:49:01+05:30

It is the horizontal row of the periodic table.

Period1 has two elements - hydrogen and helium.

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