acid

acid

CEFR: C1-C2 /acid/ [ae1.s.ah0.d]

An acid is a chemical substance that has a pH value of less than 7. An alkali is a chemical substance that has a pH value of more than 7. There are many acids and alkalis. For example:

Example Sentences:
Vinegar in a salad is an acid
Vitamin C is an acid
Salt is an alkali.
Sodium is one of the alkali metals.