Q.Define green chemistry. Write two disadvantages of nanotechnology.

Green Chemistry is defined as the use of chemistry for pollution prevention, through environmentally conscious design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances; more broadly, it is an approach to chemistry that aims to maximise efficiency while minimising hazardous effects on human health and the environment. The concept was coined by Paul T. Anastas (born 16 May 1962), director of Yale University's Center for Green Chemistry and Green Engineering and known as the father of green chemistry, who also enunciated its twelve founding principles. Green chemistry is closely tied to sustainable development, defined as development that meets the needs of the present without compromising the ability of future generations to meet their own needs -- a definition that has continued to evolve to also emphasi …