A solution with a pH value less than 7 is a/an:

The pH scale is a logarithmic measure used to quantify the acidity or basicity of an aqueous solution, typically ranging from 0 to 14 [3]. A pH value of 7 is considered neutral, representing a state where the concentrations of hydrogen (hydronium) ions and hydroxide ions are equal, as seen in pure water [3]. Solutions with a pH value less than 7 are classified as acidic, characterized by a higher concentration of positively charged hydrogen ions [3]. Conversely, solutions with a pH greater than 7 are basic or alkaline [3]. While the term 'hypotonic' refers to a solution's osmolarity and its effect on cell volume through osmosis, it is unrelated to the pH scale [2]. Therefore, a solution with a pH less than 7 is definitively an acidic solution.

Sources

1. [3] https://www.ncbi.nlm.nih.gov/books/NBK557609/
2. [1] https://www.usgs.gov/media/images/ph-scale-0
3. [2] https://ecology.wa.gov/es-es/blog/february-2014/let-s-talk-science-a-ph-solution