About б, д, г, ґ, з, ж at the end of a word:
Voiced consonants at the end of a word don't become unvoiced, they don't change to the corresponding unvoiced ones: [горб], [с΄н΄іг], [нарóд], [д΄ід], [стóрож], [змерз].
There are also voiced affricates "дж", "дз", and "дз΄" in Ukrainian (each of them is pronounced as one indivisible sound). E. g. the transcription of the word "ґедзь" will be [ґедз΄] (the last sound remains voiced).

About unvoicing:
Voiced consonants before unvoiced ones (in the middle of a word) don’t become unvoiced either: [гýбка], [кáзка], [н΄і΄жка], [грýдка], [поб’і΄гтие], [розкажý], [беизхвóстиĭ], except [г], which changes into [х] in several words: [лéхко], [вóхко], [н΄і΄хт΄і], [к΄і΄хт΄і]. З can become unvoiced only in the preposition / prefix з before [к], [п], [т], [ф], [х]: [c хáтие]. And in the prefixes роз- and без- з can be pronounced both voiced and unvoiced: [беиспéчниĭ], [беизпéчниĭ].

About в:
В is pronounced as the consonant only before vowels: [вагá], [вóрон], [вýзол], [весь], [вúхор], [вíтер]. At the beginning of a word before consonants and at the end of a word / a syllable it becomes the vowel [ў] (this vowel doesn’t form a syllable): [ўчóра], [ўдвójеи], [стаў], [буў], [воўкú], [стáўтеи].

About voicing:
When unvoiced consonants precede voiced ones in the middle of a word, they become voiced: [бород΄бá], [прúз΄ба], [анеиґдóт].