Я ховаю паспорт у шухляду, щоб не загубити його.

That’s true: Ukrainian often omits subject pronouns because the verb ending already shows the person.

• ховаю = I hide / I am putting away
• so Я ховаю and just ховаю can both work

Including Я can:

• make the sentence clearer out of context
• add a little emphasis
• sound more natural when starting a new statement

So Я is not required, but it is perfectly normal.

Ховати / ховати usually means to hide, but in everyday use it can also mean to put something away somewhere safe.

In this sentence, Я ховаю паспорт у шухляду sounds like:

• I put my passport away in a drawer
• I hide my passport in a drawer
• I tuck my passport into a drawer for safekeeping

So it is not necessarily secretive; it often just means putting something somewhere so it won’t get lost.

Паспорт is in the accusative case because it is the direct object of ховаю.

The useful detail is:

• masculine singular inanimate nouns often have the same form in the nominative and accusative

So:

• nominative: паспорт
• accusative: паспорт

That is why the form does not change.

Because this sentence expresses movement into the drawer, not location inside it.

• у шухляду = into the drawer → accusative
• у шухляді = in the drawer → locative

Compare:

• Я кладу паспорт у шухляду. = I put the passport into the drawer.
• Паспорт лежить у шухляді. = The passport is in the drawer.

This is a very common Ukrainian pattern:

• motion/direction → accusative
• location → locative

Yes, у and в are often interchangeable, and the choice is usually made for euphony—to make the sentence easier to pronounce.

Here, паспорт у шухляду flows more smoothly than паспорт в шухляду, which creates a heavier consonant cluster.

So the difference here is not one of meaning, but mostly sound.

Щоб introduces a purpose clause. It means something like:

• so that
• in order to

So:

• Я ховаю паспорт у шухляду, щоб не загубити його.
• I put my passport in the drawer so that I don’t lose it / in order not to lose it.

It connects the main action with the purpose behind it.

After щоб, Ukrainian often uses the infinitive when the subject is understood and does not need to be repeated.

So щоб не загубити його literally means:

• so as not to lose it
• in order not to lose it

This is very natural Ukrainian.

You could also have a finite verb after щоб in other contexts, especially when the subject is stated more explicitly, but here the infinitive is the standard and compact choice.

Because загубити is perfective, and that fits the meaning here.

• губити = imperfective, to be losing / to lose repeatedly / to misplace
• загубити = perfective, to lose once, as a completed event

In this sentence, the speaker wants to prevent one whole result:

• not to lose the passport

That is why загубити is the natural choice.

Yes, його refers back to паспорт.

Ukrainian often uses the pronoun in a purpose clause like this, just as English often says lose it rather than repeating the noun.

So:

• щоб не загубити його = so as not to lose it

Could the pronoun be omitted in some contexts? Sometimes Ukrainian leaves things implied, but here його sounds natural and clear.

That is the normal position here.

In Ukrainian, object pronouns often come after the infinitive or verb:

• загубити його = lose it

Putting його before the verb is possible only in special contexts for emphasis or contrast, but the neutral order is:

• не загубити його

Because щоб не загубити його is a subordinate clause of purpose, and Ukrainian normally separates such clauses with a comma.

So the structure is:

• main clause: Я ховаю паспорт у шухляду
• subordinate purpose clause: щоб не загубити його

That is why the comma is required.

Yes. Ukrainian word order is fairly flexible, although some versions sound more neutral than others.

The given sentence is natural and neutral:

• Я ховаю паспорт у шухляду, щоб не загубити його.

You could also hear variations such as:

• Паспорт я ховаю у шухляду, щоб не загубити його.
  This emphasizes паспорт.
• Щоб не загубити його, я ховаю паспорт у шухляду.
  This emphasizes the purpose first.

So the meaning stays similar, but the focus changes.