How do the valency and the atomic size of the element vary while going from left to right along a period in The modern periodic table?​

Atomic size decreases on going along a period from left to right because the electron enters into the same shell, therefore, attraction between nucleus and outermost electron increases and thus atomic size decreases. Valency first increases from 1 to 4 and then decreases from 4 to GO along a period from left to right.

here is table 2-2:

country

percent of eligible voters that voted

rank

united states

44.9%

138

canada

60.1%

107

costa rica

84.6%

14

hungary

66.9%

82

japan

57.0%

118

egypt

27.7%

159

south africa

85.5%

10

ans is no, the data set cannot be plotted as a single circle graph