Question

Are ethan-1-al and ethanal both correct?

Answer 1

Yeah both are same and correct..

Answer 2

yes

listen if you have confusion in such type of questions, start making structures.

Pehle toh yeh ki ye isliye correct hai kyunki ethan-2-al doesn't exist matlab sirf ek hi CHO ho sakta hai.

confusion hatane ke liye iss type ke questions mein -2 ya3 ya4 ...etc naam likhkar uske structure banao. Maana ye tarika bada hai par aapko baad mein chalkar kabhi confusion nhi hoga aur aap nomenclature mein perfect ho jaoge.

Hope it helps.

For more explanation do comment.