Physics
It is easy to burst a gas-filled balloon with a needle than with a nail. It is because

Nail is more longer than needle.
Needle exerts more pressure than nail on the balloon.
Nail exerts more pressure than needle on the balloon.
Gas is reactive with the needle.

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Physics
A white and smooth surface is

Bad absorber and bad reflector of heat
Good absorber and good reflector of heat
Bad absorber and good reflector of heat
Good absorber and bad reflector of heat

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