Question

Is this the structure for 2-methylbut-1-ene?

----H---H--CH3----H
-----I----I----I-------/
H - C - C - C = C
-----I----I------------\
-----H--H------------H

I was told in the question asking to draw the condensed formula for 2-methylbut-1-ene that "bonds are not shown, for example propanol is CH3CH2CH2OH".

Is this the condensed formula for 2-methylbut-1-ene that I write?

H3CCH2C(CH3)CH2

Is this the condensed formula for 2-methylbut-1-ene that I write?

H3CH2C(CH3)=CH2

Does it matter if it says H3C or CH3 at the beginning of the formula?

Answer 1

Is this the structure for 2-methylbut-1-ene?

----H---H--CH3----H
-----I----I----I-------/
H - C - C - C = C
-----I----I------------\
-----H--H------------H
yes, this is the structural formula

I was told in the question asking to draw the condensed formula for 2-methylbut-1-ene that "bonds are not shown, for example propanol is CH3CH2CH2OH".
You have written the condensed formula for n-propanol. The condensed formula for 2-methylbut-1-ene is CH3CH2C(CH3)=CH2

Is this the condensed formula for 2-methylbut-1-ene that I write?

H3CCH2C(CH3)CH2
No, you omitted the double bond. See the structure I drew above.

Is this the condensed formula for 2-methylbut-1-ene that I write?

H3CH2C(CH3)=CH2
No you left out a C atom. You wanted H3CCH2C(CH3)=CH2methylproan-1-ene

Does it matter if it says H3C or CH3 at the beginning of the formula?
No, none at all. When I was a student many years ago we ALWAYS wrote it as CH3. In recent years some authors like the H3C but in reality they are the same.