Alkenes, Alkanes and so on?

I know Alkanes have this formula: CnH2n +2

Alkenes and cycloalkanes have this: CnH2n

Etyns and Cycloalkenes have this: CnH2n -2

Is this correct? Please correct me!

Answer:
absolutely correct
u just have to think about the bonding.
normal alkAnes have for only CH2 groups and 2 CH3 groups at both ends (the calculation is also valid for isomers, since carbon is always 4-valent and there are only C-H and C-C bonds). so to every C there are 2H (to make CH2) plus an extra 2H (those at both ends of the molecule) that make the CH3. so therefore formula is C(n)H(2n+2).
if we go to the alkEnes, they have 1 double bond. this means 2 C´s are bonded to one another, instead of to one H each. meaning they have 2H´s less than normal alkanes,therefore, for simple alkenes the formula is C(n)H(2n).
the same goes for cycloalkenes-there u have no CH3 at both ends-it´s a cycle, remeber? so again, 2H´s less than normal alkanes.

if we do the same reasoning with alkynes, we come up with 2H´s less than alkEne, namely C(n)H(2n-2).

this is of course valid for mono-alkenes and -alkynes.
every other double bond or cycle reduces the number of H´s by two.
there is also the s.c. unsaturation degree, to help u figure it out
http://www.chemhelper.com/alkeneunsatura...
Alkanes Have formula CnH2n+2

Alkenes have formula CnH2n
and
Alkynes have formula CnH2n-2
yes, you are right,

Alkanes have formula CnH2n +2

Alkenes and cycloalkanes have formula CnH2n

Alkynes and Cycloalkenes have formula CnH2n -2
Sorry you are wrong..Alkynes have CnH2n - 2
correct
it is correct ,why you have confusion
yes
perfect score.
It is correct.Here n indicates the no of carbon atoms.If you have doubt that this is wrong then you can confirm it by some examples.e.g.Ethane is an alkane with the formula C2H6.Here n is equal to 2

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