World Geography
The major events of Pre-Cambrian era include

All of these
formation of crust, continents and oceans
formation of present day atmosphere
formation of crust, birth of oldest known rock, origin of life

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World Geography
The initial increase of magnetic field in magnetic storms is caused

when there is a large decrease in field intensity
None of these
when the gust wind itself engulfs the magnetosphere
when the shock wave, associated with the gusty solar wind, compresses the magnetosphere

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