Which enzyme or substance is responsible for the conversion of milk into curd?

What happens when: $(i)$ ethanol is burnt in air and $(ii)$ it is oxidized? Write the corresponding reaction equations.

An atom of an element contains six electrons in its valence shell. This element is the second major component of air. It exists as a diatomic molecule.
$(i)$ Identify the element.
$(ii)$ Show the bond formed between two atoms of this element.
$(iii)$ Write the nature of the bond between the two atoms.

Which of the following is used in conveyor belts?

What conversion occurs in the formation of milk into curd?

Draw the possible isomers of the compound with molecular formula $C_3H_6O$ and also give their electron dot structures.