Lactic acid on heating with conc. $H_2SO_4$ gives

Ozonolysis of an organic compound gives formaldehyde as one of the products. This indicates the presence of:

What is the product of the following reaction?

When neopentyl alcohol is heated with an acid,it slowly converts into an $85:15$ mixture of alkenes $A$ and $B$,respectively. What are these alkenes $?$ (Note: $A$ is the major product and $B$ is the minor product.)

Compound $(A)$ is formed by the reaction of cyclooctatetraene with $(3 \text{ mole})$ of $CH_2I_2$ in the presence of $Zn/Cu$. Identify compound $(A)$.

Position of a double bond in an organic compound is determined by