يوجد دواء في الحقيبة الآن.

يوجد literally means “(it) exists / there is”. In Modern Standard Arabic it’s commonly used like English “there is/are” to introduce something’s existence or presence.
Pattern: يوجد + (noun) + (place/time info)
So يوجد دواء... = “There is medicine...”.

Arabic often keeps يوجد in the singular form regardless of whether the following noun is singular or plural, especially in straightforward statements. You can say:

• يوجد دواء = there is medicine
• يوجد أدوية = there are medicines
  So you don’t need a different verb form the way English switches between is/are.

Because the sentence is introducing an item as some medicine / a medicine (not a specific, already-known one). In Arabic, this is normally expressed with an indefinite noun: دواء (no الـ).
If you meant the (specific) medicine, you might say يوجد الدواء في الحقيبة الآن (context-dependent).

In Arabic, the indefinite singular can cover both readings depending on context:

• دواء can mean “a (dose/type of) medicine” or “medicine (some medicine)”.
  If you want to clearly express “some medicine,” Arabic may still just use دواء; context usually resolves it.

Because في is a preposition meaning “in”, and it introduces a prepositional phrase indicating location. Arabic uses prepositions similarly to English here:

• في الحقيبة = in the bag
  This is not a direct object; it’s a location phrase modifying the existence statement.

Often, Arabic uses الـ when the listener can identify the noun from context (e.g., the bag you’re talking about). In many everyday contexts, “the bag” sounds natural even in English.
You can make it indefinite too: في حقيبة = in a bag, if you mean any bag.

In careful MSA with case endings:

• يُوجَدُ دَوَاءٌ فِي الحَقِيبَةِ الآنَ.
  Typical analysis:
• يوجد = verb (present)
• دواءٌ is often treated as the “thing found/exists” (commonly described as the نائب فاعل in passive-like analysis, or as the subject of the existence statement depending on grammar tradition); it appears nominative with -ٌ.
• في الحقيبةِ: الحقيبةِ is genitive after في.
• الآنَ is usually accusative as an adverb of time.

(Real-life pronunciation often drops these endings, especially outside very formal settings.)

A very common alternative is هناك (“there is/are”):

• هناك دواءٌ في الحقيبة الآن.
  Both are correct in MSA. يوجد can sound slightly more “formal/explicit existence,” while هناك is very common and natural for simple “there is/are” statements.

In standard pronunciation for “to exist/be found,” it’s يُوجَدُ (passive-like form meaning “is found/exists”).
يُوجِدُ (with kasra on the jīm) would mean “causes to exist / creates / brings about” (active causative sense), which is a different meaning. For this sentence, you want يُوجَدُ.

الآن is flexible. Common options:

• يوجد دواء في الحقيبة الآن.
• يوجد الآن دواء في الحقيبة.
• الآن يوجد دواء في الحقيبة.
  All can work; the position can slightly change emphasis (putting الآن earlier emphasizes “now”).

Yes. Without it, the sentence just states location generally:

• يوجد دواء في الحقيبة. = There is medicine in the bag.
  Adding الآن adds a time meaning: it’s there now (maybe not always).

You can make a nominal-style sentence, but Arabic commonly uses هناك or يوجد for “there is/are.” A bare nominal sentence like دواء في الحقيبة is more like a label/telegraphic style (e.g., notes, headlines). For a full standard sentence, يوجد/هناك is preferred.

Common MSA negation options:

• لا يوجد دواء في الحقيبة الآن. = There is no medicine in the bag now.
• ليس هناك دواء في الحقيبة الآن. = There isn’t any medicine in the bag now.
  Both are widely used; لا يوجد is very straightforward.

You can add the question particle هل at the beginning:

• هل يوجد دواء في الحقيبة الآن؟ = Is there medicine in the bag now?
  In writing, you use the Arabic question mark ؟.

A common way is:

• ماذا يوجد في الحقيبة الآن؟ = What is in the bag now?
  Or more formal:
• ما الذي يوجد في الحقيبة الآن؟