Question

Give reason for the following

Formation of curd from milk is a chemical change

Answer 1

Changes of matter is classified into two, physical and chemical changes

• Formation of curd from milk is a chemical change, where curd is a new substance formed there
• It is not possible to convert curd into milk back
• The bacteria lactobacillus convert milk into curd by some chemical activities
• Therefore, the formation of curd from milk is a chemical change

Physical changes	Chemical changes
Changes which involve only physical properties like color, appearance etc..,	Changes which involves chemical properties like nature of bonding, energy etc.,
Generally, no new substances are formed	Generally, new substances are formed
Generally, it doesn't involve with heat, energy change	It involves with heat, energy change