Cotyledons are special structures in the seeds of the plants. Cotyledons store food for the embryo of the plant. In gram seeds, there are two cotyledons and in maize (com) seeds, there is only one cotyledon.
When hard water is used in these bioilers, then white scum of salts present in the hard water gets deposited inside the boilers making a white layer. These white layers can be removed by washing the boilers with dil. HCl acid.
