Which are the standard meridians of (a) Russia (b)Brazil (c) France (d) South Africa (e) Australia?
Unlike latitude which is defined by the rotation of the Earth, longitude is arbitrarily defined; we could have put the prime meridian wherever we wanted, and actually until an international conference standardized it at Greenwich different countries put it in different places.
The standard meridians are those which are at 15-degree offsets from that Greenwich prime meridian, and they are roughly aligned with the time zones because 360/15 = 24.
Russia has a whole bunch of them; all the meridians from 30 to 180 all pass through Russia, so its standard meridians are 30, 45, 60, 75, 90, 105, 120, 135, 150, 165, 180.
Brazil contains standard meridians -45 and -60.
France contains only the 0 standard meridian, the same one as Greenwich.
South Africa contains the 30 standard meridian.
Finally, Australia contains 120, 135, and 150.