Answer:
The correct option is : Their atoms have eight electrons in their valence shells, so noble gases are very unreactive.
Explanation:
The octet rule state that atoms tend to complete their last energy levels with eight electrons, and that this configuration make them very stable and unreactive.
Noble gases are characterized as unreactive atoms, and this is associated with the fact that they have a complete valence shell, it means that they have eight electrons on it (they follow the octet rule).
Atoms with less electrons on their valence shells tend to react with another atom, forming bonds, to complete their valence shells (with eight electrons).
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:
W=f*d
= 50 * 15
=750 J
Therefore, the work done is 750 joule( J)
