Two carbon atoms cannot be linked to each other by more than three covalent bonds why

since,there is a single bond between the two carbon atoms and both share their one atom therefore for completing its shell it need to combine with three atoms of carbon or other element . therefore it cannot be linked to more than 3 covalent bonds since its shell will be completed to become stable .

Explanation:

warm front forms when a moist, warm air mass slides up and over a cold air mass. as the warm air mass rises, it condenses into a broad area of clouds. a warm front brings gentle rain or light snow, followed by warmer, milder weather.

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