Question

mention the main sources of information of medieval period

Answer 1

Literary Sources. Letters ,Writing and Speeches Provided by the kings are thr main sources of infotmation of medieval period. You can find these typrs of book in library.....

Answer 2

(i) Elements are arranged in the order of increasing atomic mass.
(ii) There are nine vertical columns called groups.
(iii)Transit elements are arbitrarily placed together in group 8
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