can i use 30W macbook air adaptor to charge my ipad pro 2020 model 12.9 inches

The Apple 30W Power Adapter is actually an excellent choice for charging your iPad. Whilst your iPad Air2 does not support USB PD (Power Delivery) - and therefore cannot benefit from Fast Charging - your iPad will safely charge at its maximum supported charging rate of 12W (i.e., 2.4A @5V).

Yes

Yes you can.

-have a good day.

Yes.

No problems. No worries.