What is the general formula for alkanes?

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Multiple Choice

What is the general formula for alkanes?

Explanation:
Alkanes are saturated hydrocarbons with only single bonds between carbon atoms. For an open-chain alkane with n carbon atoms, there are n−1 carbon–carbon single bonds. Each carbon wants four bonds, so the total number of bonds needed is 4n. The carbon–carbon bonds use up 2(n−1) of those, leaving 4n − 2(n−1) = 2n + 2 bonds to be filled by hydrogen. Therefore, the general formula is CnH2n+2. For example, one carbon gives CH4, two carbons give C2H6, and three carbons give C3H8, all fitting the same pattern. If you had double bonds or rings, hydrogens would be fewer, which is why alkenes and cycloalkanes have different formulas like CnH2n or similar.

Alkanes are saturated hydrocarbons with only single bonds between carbon atoms. For an open-chain alkane with n carbon atoms, there are n−1 carbon–carbon single bonds. Each carbon wants four bonds, so the total number of bonds needed is 4n. The carbon–carbon bonds use up 2(n−1) of those, leaving 4n − 2(n−1) = 2n + 2 bonds to be filled by hydrogen. Therefore, the general formula is CnH2n+2. For example, one carbon gives CH4, two carbons give C2H6, and three carbons give C3H8, all fitting the same pattern. If you had double bonds or rings, hydrogens would be fewer, which is why alkenes and cycloalkanes have different formulas like CnH2n or similar.

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