Der Kragen meines Hemdes ist noch nicht trocken.

Because Kragen is the subject of the sentence, so it is in the nominative case.

• der Kragen = nominative
• den Kragen = accusative
• dem Kragen = dative

In Der Kragen meines Hemdes ist noch nicht trocken, the collar is the thing being described, so German uses the nominative: der Kragen.

This is the genitive case, which often shows possession or a close relationship.

• der Kragen = the collar
• meines Hemdes = of my shirt

So literally, the structure is:

• der Kragen meines Hemdes = the collar of my shirt

English often uses of or ’s, but German can use the genitive instead.

Because both the possessive word and the noun have to show the genitive singular.

• mein Hemd = my shirt
• meines Hemdes = of my shirt

Here is what changes:

• mein → meines
• Hemd → Hemdes

That happens because Hemd is a neuter noun, and in the genitive singular, neuter nouns often take -es on the noun, while mein- takes the ending -es as well.

Because many masculine and neuter nouns in German add -s or -es in the genitive singular.

So:

• das Hemd = the shirt
• des Hemdes = of the shirt

With a possessive:

• mein Hemd
• meines Hemdes

For Hemd, the genitive form Hemdes is standard. In some nouns, German uses just -s, but -es is very common and often sounds more natural with short words like this.

Yes, you can, especially in everyday spoken German.

• der Kragen meines Hemdes = more formal or written-style
• der Kragen von meinem Hemd = very common in speech

Both are understandable. A learner should recognize both, but the sentence you were given is a very good example of the genitive, which is important to learn.

Because trocken is a predicate adjective here, used after sein.

In German, adjectives used after verbs like sein, werden, or bleiben do not take adjective endings.

So:

• Das Hemd ist trocken.
• Der Kragen ist trocken.

But before a noun, the adjective does take an ending:

• ein trockener Kragen
• das trockene Hemd

So in your sentence, trocken stays plain because it comes after ist.

Because German main clauses usually follow the V2 rule: the finite verb comes in the second position.

In this sentence:

• Der Kragen meines Hemdes = first element
• ist = second position
• noch nicht trocken = the rest

So the sentence follows normal German word order.

Noch nicht means not yet.

• nicht trocken = not dry
• noch nicht trocken = not dry yet

The word noch adds the idea that the situation may change later. So the collar is currently still not dry, but it probably will become dry.

Nicht trocken is not wrong, but it means something slightly different.

• nicht trocken = not dry
• noch nicht trocken = not dry yet

So noch nicht adds the idea of up to now or so far.

Compare:

• Der Kragen ist nicht trocken.
  This simply states that the collar is not dry.
• Der Kragen ist noch nicht trocken.
  This suggests it is still drying and may be dry later.

Here, nicht comes before trocken because it is negating the adjective trocken.

• ist noch nicht trocken

In other words, the sentence is saying the collar is not dry yet.

A useful pattern is:

• Er ist nicht müde.
• Das Essen ist nicht warm.
• Der Kragen ist noch nicht trocken.

When nicht negates an adjective, it usually comes right before that adjective.

Because meines Hemdes belongs closely to Kragen. It tells you which collar we mean.

So the full noun phrase is:

• Der Kragen meines Hemdes

That whole phrase acts as the subject of the sentence. Only after the complete subject do we get the verb:

• Der Kragen meines Hemdes ist ...

This is very similar to English:

• The collar of my shirt is ...

No. In German, grammatical gender does not always match real-world gender.

Hemd is grammatically neuter:

• das Hemd

That is just the grammatical gender of the word. It does not mean the shirt itself is somehow neutral in a real-life sense.

In theory, German can move elements around, but that version sounds very unnatural here.

The normal and natural order is:

• Der Kragen meines Hemdes ist noch nicht trocken.

You could also front another element for emphasis, for example:

• Noch ist der Kragen meines Hemdes nicht trocken.

That means something like The collar of my shirt still isn’t dry and puts more emphasis on still. But for learners, the original version is the best basic pattern.

The German structure is a bit more literal as:

• The collar of my shirt is still not dry.

Natural English usually prefers:

• The collar of my shirt isn’t dry yet.

That helps show why noch nicht corresponds so well to not yet.