A minute of arc is \(π\over 10800\) of a radian.

A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol ″, is \(1\over60\) of an arcminute, \(1\over3600\) of a degree, \(1\over1296000 \)of a turn, and \(π\over648000\) (about \(1\over206369\))

so answer is,

(2) 4.85 × 10^{–6}