Érase una vez (= 'Once upon a time'. Don't know why someone offered this)
'Why would you' lacks a main verb (e.g. 'Why would you (live in Spain)?', which translates as ¿Por qué vivirías en España?').
¿Por qué? (Why?) is no problem; but '...would you' only functions in Spanish as part of the main verb (in the example given, as '....irías').
So you need to specify the main verb (or if this is in response to a statement, the main verb implied from the statement, e.g. 'I'd never eat glass.' 'Why would you (eat glass)?' - 'Yo nunca comería vidrio.' '¿Por qué comerías vidrio?')
To say 'I have a microwave' in Spanish, you would say 'Tengo una microonda.'
To say 'I have a notebook' in Spanish, you would say 'Tengo un cuaderno.'
To say 'furniture shop' in Spanish, you would say 'muebleria.'
To say 'rich' in Spanish, you would say 'rico.'
To say 'knives' in Spanish, you would say 'cuchillos.'
To say 'condensation' in Spanish, you would say 'condensación.'
To say 'evaporation' in Spanish, you would say 'evaporación.'
To say 'decompostion' in Spanish, you would say 'descomposición.'
You would say "español". It is not normally capitalized.
To say "to skate" in Spanish, you would say "patinar".
To say 'cow' in Spanish, you would say 'vaca.'
To say I am not dark in Spanish, you would say: I ser no oscuro