A carga horária está no contrato de trabalho.

Not exactly. Carga horária usually means the required number of working or study hours attached to a job, course, or activity.

In this sentence, it refers to the work schedule / required working hours stated in the employment contract.

So it is broader than just hours. It often implies:

• how many hours someone is expected to work
• sometimes the official weekly or monthly hour load

For example:

• A carga horária é de 40 horas semanais. = The workload / required hours are 40 hours per week.

Portuguese often uses definite articles much more than English does.

So A carga horária literally has the before it, even where English might simply say:

• Work hours are in the employment contract
• or The working hours are in the employment contract

Using the article here sounds natural in Portuguese. Leaving it out would usually sound incomplete or unnatural in a normal sentence.

Because estar is used to talk about location.

Here, the sentence says where the work-hour information is found:

• A carga horária está no contrato de trabalho.
• Literally: The workload is in the employment contract.

Portuguese normally uses estar for physical or figurative location:

• O livro está na mesa.
• A informação está no documento.

If you used é, it would suggest identity or definition, not location, so it would sound wrong here.

No is a contraction of:

• em + o = no

So:

• no contrato = in the contract

This contraction is required in normal Portuguese.

Other common contractions:

• na = em + a
• nos = em + os
• nas = em + as

Examples:

• na empresa = in the company
• nos documentos = in the documents

So em o contrato is not the normal form.

De trabalho means of work or, more naturally in English, employment / work-related.

So:

• contrato de trabalho = employment contract / work contract

Portuguese often uses de + noun where English uses a noun as an adjective.

Compare:

• cartão de crédito = credit card
• mercado de trabalho = job market
• horário de trabalho = work schedule

So de trabalho is describing what kind of contract it is.

Because horária agrees with carga, which is a feminine noun.

In carga horária:

• carga = feminine
• horária = feminine singular adjective

That is why you get:

• a carga horária

If the noun were masculine, the adjective would change too.

This is one of the key features of Portuguese: adjectives often agree in gender and number with the noun.

Grammatically, it is singular.

The whole expression carga horária is treated as one unit meaning something like:

• workload
• required hours
• hour requirement

That is why the verb is singular:

• A carga horária está...

Even though the idea involves multiple hours, the expression itself is a singular noun phrase.

Yes, but the meaning changes.

As cargas horárias would mean the workloads / hour requirements in the plural. That would make sense only if you are talking about:

• several positions
• several employees
• several programs or schedules

For one job or one contract, singular is the natural choice:

• A carga horária está no contrato de trabalho.

Yes, it is natural and correct.

It sounds like something you might see in:

• HR communication
• legal or administrative contexts
• workplace explanations

Depending on context, Brazilians might also say:

• A carga horária consta no contrato de trabalho.
• A jornada de trabalho está no contrato.
• Essa informação está no contrato de trabalho.

But your original sentence is perfectly normal.

They are related, but not always identical.

• carga horária usually focuses on the number of required hours
• jornada de trabalho often refers more to the workday/work schedule arrangement, such as start and end times or the structure of the working day

For example:

• A carga horária é de 40 horas semanais.
• A jornada de trabalho é das 9h às 18h.

In real usage, though, people sometimes use them in overlapping ways.

Yes, if the context already makes it clear which contract you mean.

So both are possible:

• A carga horária está no contrato de trabalho.
• A carga horária está no contrato.

The longer version is more explicit and is especially useful when:

• you want to be formal
• there could be more than one kind of contract
• you want to avoid ambiguity

A careful Brazilian Portuguese pronunciation would be approximately:

a KAR-ga o-RAH-rya es-TAH nu kon-TRA-tu dji tra-BA-lyu

A few useful notes:

• horária has stress on rá
• está has stress on the last syllable
• no sounds like nu in many Brazilian accents
• de trabalho is often pronounced more like dji trabalho in Brazil
• the lh in trabalho sounds like the lli in million for many English speakers

Yes, but the original order is the most neutral.

Natural versions include:

• A carga horária está no contrato de trabalho.
• No contrato de trabalho está a carga horária. — more marked, less neutral
• A carga horária está no contrato. — shorter

Portuguese allows some flexibility, but for a learner, the original sentence is the best standard pattern to follow:

• subject + verb + location

No. It is also very common in education and training.

For example:

• O curso tem carga horária de 60 horas. = The course has a 60-hour workload.
• A disciplina possui carga horária reduzida. = The subject has a reduced number of hours.

So the phrase is widely used for:

• jobs
• courses
• academic programs
• internships
• training programs