You asked

Is the sony fe 40mm f 2 5 g good on aps c?

Here is what the site says about that.

From Sony FE 40mm f/2.5 G: Sony FE 40mm f/2.5 G: A prime lens by Sony for Full frame cameras, 40mm f/2.5. Tiny and sharp: a lovely everyday lens on the compact bodies. Specs - Maker: Sony - Focal length: 40mm (prime) - Maximum aperture: f/2.5 - Made for: Full frame sensors - Mounts: Sony E - Stabilised: no - Autofocus: yes What it frames like - On full frame (Sony E): as marked, 40mm. - On APS-C (Sony E): like ...

From Sensor sizes: What a bigger sensor buys you: - Better low light. At the same framing and the same f-number, a bigger sensor collects more light in total, so images are cleaner at high ISO. Roughly, full frame has about one stop of advantage over APS-C, and two over Micro Four Thirds. - Shallower depth of field. At the same framing and f-number, a bigger sensor gives more background blur. An f/1.8 lens on APS-C gives about the ...

Quoted from this site's pages.

From these pages