Do they exchange rupees for dollars at Sri Lanka airport?

Yes, at Colombo International Airport and Mattala Rajapaksa Airport you can exchange rupees for dollars or euros, but only if you have a receipt of exchanging dollars for rupees. That is, if you exchange money only at private exchange offices at resorts without issuing a receipt, you will not be able to exchange back at the airport. Read more about everything you need to know about money in Sri Lanka here - https://nashaplaneta.net/asia/srilanka/valuta-sri-lanka

How much does a visa to Sri Lanka cost?
Where to buy alcohol on the island?
Which resort do you recommend for the first time?
Follow the link, all these questions are discussed in the chat - https://t.me/srilanka_travel_chat