Learn Hardcore French: Le micro-ondes est utile quand nous avons peu de temps, mais le four est plus utile pour les gâteaux. - The microwave is useful when we have little time, but the oven is more useful for cakes.

Because it’s a compound noun formed from micro + ondes (“waves”). The device works with microwaves, so the second element stays plural. The word is masculine: le micro-ondes. For the plural device name, you’ll still see an -s on both parts: des micro-ondes, or more explicitly des fours à micro-ondes.

Is le micro-ondes correct, or should I say le four à micro-ondes?

Both are common. Le four à micro-ondes is the full, more formal term; le micro-ondes is a very common shortened form in everyday speech. In careful writing, many prefer the full form. You’ll also see set phrases like mettre au micro-ondes (“put in the microwave”).

Why is it le (the) micro-ondes and le four? In English we’d often say “a microwave/oven.”

French typically uses the definite article (le/la/les) to make general statements about a category. So Le micro-ondes est utile… means “Microwaves are useful…” in a general sense. Same idea with Le four est…

Why is it peu de temps and not un peu de temps? And why not peu du temps?

peu de = little/not much (scarcity): peu de temps (“not much time”).
un peu de = a little/some: un peu de temps (“a little time”). After quantity words (peu de, beaucoup de, assez de, etc.), French uses bare de, not a partitive: hence not peu du temps.

Can I use on instead of nous? For example, quand on a peu de temps?

Yes. On is very common in speech for “we/people/one” and sounds natural: Quand on a peu de temps… In writing, nous is a bit more formal, but both are correct.

Could I use lorsque instead of quand?

Yes. Lorsque is a stylistically slightly more formal synonym of quand in temporal clauses. Both are fine: Lorsque nous avons peu de temps… Before vowels, lorsqu’ is used (e.g., lorsqu’on).

Why is it plus utile and not meilleur or mieux?

utile is an adjective; its comparative is formed with plus: plus utile (“more useful”).
meilleur(e) is the comparative of the adjective bon(ne) (“good”), used with nouns: un meilleur four.
mieux is the comparative of the adverb bien (“well”), used with verbs: Ce four cuit mieux. Here we’re comparing usefulness, so plus utile is the right choice.

Should there be a que after plus utile?

Only if you explicitly compare two things: Le four est plus utile que le micro-ondes pour les gâteaux. In the sentence given, it says “more useful for cakes” (purpose) rather than “more useful than X,” so que is not required.

Why pour les gâteaux and not pour des gâteaux or à gâteaux?

pour + noun expresses purpose: pour les gâteaux = “for cakes (in general).”
The definite article les signals a general category. pour des gâteaux would mean “for some cakes (specific, not general).”
à is not used here; it appears in set compounds like moule à gâteau (cake tin). You can also say pour faire des gâteaux or more precisely pour cuire des gâteaux to highlight the action.

Could I say le gâteau in the singular instead of les gâteaux?

Not for a general statement. French usually uses the plural with a general category: pour les gâteaux (“for cakes” in general). Singular le gâteau would sound like you’re talking about one representative cake or a specific cake type.

How do I form the plural of gâteau?

Singular un gâteau; plural des gâteaux (add -x). Many nouns ending in -eau/-au/-eu take -x in the plural (e.g., château → châteaux, jeu → jeux).

Why temps is singular in peu de temps?

Because temps (time) is an uncountable noun in this sense. You’re talking about an amount of time, not countable units, so it stays singular: peu de temps, beaucoup de temps.

Any pronunciation tips for this sentence?

quand: the final -d is silent; it sounds like “kɑ̃”.
nous avons: make the liaison: “nou-z-avon”.
plus utile: commonly pronounced “plu zytīl” (the -s links to the vowel in utile).
les gâteaux: no liaison (gâteaux starts with a consonant); “lé gato”.
micro-ondes: the -s is silent; “mikro-ond” (with nasal “on”).

Is the comma before mais required?

Yes, placing a comma before mais to separate the two clauses is standard and recommended: …, mais… It mirrors how you’d pause in speech.

Could I swap the clause order?

Yes: Quand nous avons peu de temps, le micro-ondes est utile, mais le four est plus utile pour les gâteaux. Both orders are natural; putting the time clause first emphasizes the condition.