(i) The acids which are obtained from plants and animals are called organic acids.
Citric acid is obtained from the lemon.
Vinegar contains acetic acid.
(ii) Concentrated acids are very hot when they fall on any object (clothes or skin), they burn the object.
(iii) Cold drinks, chocolates and sweets are most harmful to health as well as a tooth. They produce acids in the mouth which are responsible for tooth decay. It has been noticed that tooth gets dissolved in the cold drinks if kept for long time .