The chemical used to double the chromosome number is

Solution(By Examveda Team)

The chemical used to double the chromosome number is colchicine.
Colchicine is an important mutagen that works by preventing the formation of microtubules and doubles the number of chromosomes. It is commonly used to develop polyploid plants and functions as a mitotic poison by producing many mutagenic effects on plants.
The most commonly used chemical agent for chromosome doubling is colchicine, which disrupts mitosis by inhibiting the formation of spindle fibers and disturbing normal polar chromosomal migration, resulting in chromosome doubling.