"Is the lemon yellow?"
Translation:Le citron est-il jaune ?
Maybe starting with this will help you: http://french.about.com/od/questions/French_Questions.htm
Personal pronouns are not different whether the noun they represent is a human being, an animal, a concrete object or a concept.
- "il" refers to any masculine noun.
- "elle" refers to any feminine noun.
"ce" is not a neutral personal pronoun, it is a demonstrative pronoun that you can use in relation to masculine or feminine nouns but in specific constructions:
- est-ce un citron jaune ? = is it a yellow lemon?
- est-ce un homme riche ? = is he a rich man?
- est-ce une femme riche ? = is she a rich woman?