The 5v1a can be charged to an Apple x charger.
5v1a is a 5w charger, before the Apple 12, buy each mobile phone will be given a 5w charger, but I believe many people have charged, this is the Apple slow charger, to charge two or three hours to fully charge the phone, in the Apple 8 mobile phones can use fast charger, but also need to buy a separate charger.
Yes, the official standard is 5V 1000mA, that is, 5v 1a