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An element "X" has mass number 35 and the numberof neutrons, is 18. Identify the group number and periodof "X".(CBSE Sample Paper 2018) |
Answer» Given :Mass number of element is 35Number of neutrons= 18 Formula to find number of protons: Mass number = number of protons + number of neutrons.35=× +18×=35 - 18X=17.Number of protons =17 and number of electrons also will be 17 as atom is electrically neutral. Hence Element is chlorine Electronic configuraton:1s2 2s2 2p6 3s2 3p5 Group number= 17Period number =3Valency =1 |
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