WYSIWYG part deux

Here are a few more questions about acronyms and initialisms. You don’t have multiple choices today; you need to provide your own answer. What words decipher these groups of initials?

1. Often found written on the black of an envelope, what does S.W.A.L.K. mean?
2. The initialism CND refers to which British peace organisation?
3. The acronym NATO refers in full to the…
4. The acronym Qantas derives from the name of a company founded in 1920. What was the company name that Qantas spells out?
5. The acronym SONAR means what?

Good luck! I will post the answers later today.