Among the elements, `Ar, Si, Na and Cl`. Select an elements with
a. Highest `IE` b. Highest `EA`
c. Smallest size d. Highest electrical conductivity

Explanation

All of them belongs to the same `3 rd` period.
a. Highest `IE=Ar` (Since it is a nobel gas)
b. Highest `EA="Chlorine"`
`[{:("Since "EA or Delta_(eg)H^(ɵ)"invreases"),("along the period"(rarr)):}]`
`(EA "of" Cl gt F gt Br gt I)`
c. Smallest size `=` Chlorine (since size decreases along the same period `(rarr)`)
d. Highest electrical conductivity`=` Sodium [alkali metals have highest conductivity]