Questa crosta di pane è troppo dura per mia nonna.

Because crosta is a feminine singular noun in Italian.

• questo = this, for masculine singular nouns
• questa = this, for feminine singular nouns

Since crosta is feminine, the demonstrative has to agree with it:

• questa crosta = this crust

Italian words that go together usually have to agree in gender and number.

For the same reason: dura has to agree with crosta, which is feminine singular.

• duro = hard, masculine singular
• dura = hard, feminine singular

So:

• pane è duro = the bread is hard
• crosta è dura = the crust is hard

In your sentence, the subject is questa crosta, not pane, so dura is the correct form.

It means bread crust or crust of bread.

Here:

• crosta = crust
• di pane = of bread

Italian often uses noun + di + noun where English might use a compound noun:

• una tazza di tè = a cup of tea
• una fetta di torta = a slice of cake
• una crosta di pane = a bread crust / a crust of bread

Because crosta di pane is being used as a general type of thing: a bread crust.

• di pane = made of / relating to bread in a general sense
• del pane = of the bread, referring to some specific bread

So:

• crosta di pane = bread crust, the kind of crust it is
• crosta del pane = the crust of the bread, talking about a specific loaf or piece of bread

Both are possible, but they mean slightly different things.

Because è with an accent means is.

• è = is
• e = and

The accent is important because it distinguishes two completely different words.

So:

• Questa crosta di pane è dura = This bread crust is hard
• Questa crosta di pane e dura would be incorrect

Troppo means too.

So:

• dura = hard
• troppo dura = too hard

It usually goes before the adjective it modifies:

• troppo caldo = too hot
• troppo difficile = too difficult
• troppo dura = too hard

It gives the idea of excess: more hard than is acceptable or comfortable.

In this sentence, per expresses the idea of with regard to someone or for someone’s needs/abilities.

So troppo dura per mia nonna means:

• too hard for my grandmother
• too hard for my grandmother to eat/manage

Italian often uses per this way:

• È troppo pesante per me. = It’s too heavy for me.
• È troppo difficile per i bambini. = It’s too difficult for children.

So here, the crust is too hard from your grandmother’s point of view.

Because with singular family members, Italian often drops the article before the possessive.

So you usually say:

• mia madre = my mother
• mio padre = my father
• mia nonna = my grandmother
• mio fratello = my brother

Not normally:

• la mia nonna
• il mio padre

This is a very common rule with singular close family members.

Yes, but not in the neutral, ordinary form used here.

You may see the article with family members in some cases, for example:

1. When the family noun is modified

   • la mia nonna paterna = my paternal grandmother
   • il mio caro fratello = my dear brother

2. With plural family members

   • i miei fratelli = my brothers
   • le mie nonne = my grandmothers

3. In some regional or stylistic usage

   • Sometimes speakers use the article more freely

But in a simple sentence like this, mia nonna is the standard choice.

Yes. That would also be correct, but the meaning shifts slightly.

• Questa crosta di pane è troppo dura per mia nonna.

  • This bread crust is too hard for my grandmother.

• Questo pane è troppo duro per mia nonna.

  • This bread is too hard for my grandmother.

The first sentence focuses specifically on the crust. The second talks about the bread more generally.

Yes, that is possible, but it sounds more marked or expressive.

The basic neutral order is:

• Questa crosta di pane è troppo dura per mia nonna.

A reordered version like:

• È troppo dura questa crosta di pane per mia nonna.

can sound more emphatic, as if you are stressing how hard it is.

What you generally cannot do is place troppo after the adjective in the same way English sometimes moves words around. So dura troppo would usually mean it lasts too long / it endures too much in other contexts, not too hard.

A simple approximate pronunciation is:

KWEH-sta KRO-sta dee PAH-neh eh TROHP-poo DOO-ra pehr MEE-a NON-na

A few helpful notes:

• qu in questa sounds like kw
• crosta has a clear rolled or tapped r
• pane has two syllables: PA-ne
• troppo has a double p, so the consonant is held a bit longer
• nonna also has a double n, which is important in Italian pronunciation

Double consonants matter in Italian, so troppo and nonna should be pronounced more distinctly than they might be in English.

Yes, very often that is the implied idea.

The full meaning is something like:

• This bread crust is too hard for my grandmother
• This bread crust is too hard for my grandmother to eat
• This bread crust is too hard for my grandmother to handle

Italian often leaves that extra part unstated when it is obvious from context.

If you wanted to make it more explicit, you could say:

• Questa crosta di pane è troppo dura da mangiare per mia nonna.

But the original sentence is perfectly natural and simpler.

Here is a breakdown:

• Questa = demonstrative adjective, feminine singular, this
• crosta = noun, feminine singular, crust
• di pane = prepositional phrase, of bread / bread
• è = verb essere, third person singular present, is
• troppo = adverb, too
• dura = adjective, feminine singular, hard
• per mia nonna = prepositional phrase, for my grandmother

So the structure is basically:

This + bread crust + is + too hard + for my grandmother