2,3,4,5,6 пентаметил декан​

1)

CH3 CH3 CH3 CH3

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CH3- CH- CH- CH- CH- C- CH2-CH3

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CH3 C2H5

2)

CL CL C3H7

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CH3-C-CH2-C-CH-CH2-CH2-CH3

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CL CL

3)

CH3 CH3

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CH3-CH-CH -CH -CH-CH2-CH-CH2-CH2-CH3

| | |

CH3 CH3 C3H7
Вроде так