Physics
Magnetic keepers are used to protect magnets from :

Self-demagnetization
Demagnetization due to heating
Earth's magnetic field
Effect of other magnets

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Physics
A drop of liquid assumes spherical shape because:

Intermolecular forces are strong in liquids
Inter molecular forces are weak in liquids
A sphere has the largest surface area for a given volume
A sphere has the least surface area for a given volume

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