Answer:
Photopolymerization is the term for hardening or curing the sealant or composite material by exposing the material to a curing light
Explanation:
It the process through which a photopolymer reacts to the radiations in presence of the Ultra-violet light. Photopolymers refers to those materials and liquid or the plastic resins that are hardened in presence of light source such as the lasers or the lamps. When these materials are irradiated, they undergo chemical reactions and they are hardened and become solid, and hence the process called photopolymerization. Photopolymerization is majorly used in the coating and printing industries and in also in dentistry to fill the top of teeth and prevent the cavities
Answer:
self-contained, short-term light-source
Explanation:
Answer:
Spiral galaxies consist of a flat, rotating disk of stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters.
Elliptical galaxies have smooth, featureless light-profiles and range in shape from nearly spherical to highly flattened, and in size from hundreds of millions to over one trillion stars. In the outer regions, many stars are grouped into globular clusters. Most elliptical galaxies are composed of older, low-mass stars, with a sparse interstellar medium and minimal star formation activity They are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure. Collectively they are thought to make up about a quarter of all galaxies.
irregular galaxies were once spiral or elliptical galaxies but were deformed by gravitational action. they are shapeless.
Answer:
1. D. They can be a substance, material, object or source of energy.
2. B. The properties will be different.
3. C. When two reactants form one product, the reaction is spontaneous.
