The word ‘acid’ comes from the latin word acere, which means sour . We come across a large number of that taste sour. These naturally occurring or artificially prepared substances which have sour a sour taste are known as acids or they contain acids . For example , spilt milk, curd, lemons, unripe grapes and mangoes, tamarind , apples and vinegar taste sour because they contain acid in them

* curd taste sour because of the presence of lactic acid in it .

* vinegar also taste sour tastes sour because of the presence of acetic acid ( ethanoic acid) in it