A star is formed from a Nebula (plural: nebulae). It is a cloud of dust and gas in Space. Some stars are formed at the same place where the previous star died. For example, a star explodes in supernova (such as supernova of Crab Nebula), the gasses and dust from the explosion remain behind that led to the birth of a new star.
An electric current produces a magnetic field when the current flows through a wire. The correct answer will be A.
Chemical reaction produces new substances.
If you can identify substances you look for some differents befor and after. if find then sure there was chemical reaction.
Answer: Liquefaction occurs when the structure of a loose, saturated sand breaks down due to some rapidly applied loading.
As the structure breaks down, the loosely-packed individual soil particles attempt to move into a denser configuration. Liquefaction most often occurs when three conditions are met:
loose, granular sediment or fill
saturation by groundwater
strong shaking
Relative motion is the calculation of the motion of an object with regard to some other moving object.
