You can find the answers (reshebnik) for various 8th-grade chemistry workbooks from 2017 online through several educational platforms. Since there are different authors, here are the most common resources: Popular Reshebniks for 2017 Chemistry Workbooks
This is one of the most widely used workbooks. You can find digital versions and answers on platforms like GDZ.ru or Euroki. reshebnik po tetradi khimii 8 klass 2017 onlain
Answers for the workbook accompanying this curriculum are often available on MegaResheba. You can find the answers (reshebnik) for various
Цифровые рабочие тетради к учебникам «Просвещения» you can check GdzPutina.
If you are using the workbook by Gara (often paired with Kuznetsova), you can check GdzPutina.