The BPSC (Bihar Public Service Commission) mains exam consists of several papers, each with a different duration. Let's take a closer look at the duration of each paper in the BPSC mains exam:

1. General Hindi:
- The General Hindi paper is the first paper in the BPSC mains exam.
- The duration for this paper is 3 hours.
- Candidates are required to answer questions in Hindi.
- This paper tests the candidate's proficiency in the Hindi language.

2. General Studies Paper 1:
- The General Studies Paper 1 is the second paper in the BPSC mains exam.
- The duration for this paper is 3 hours.
- This paper covers various topics related to General Studies including Indian History, Geography, Politics, Economy, and Science.
- Candidates are expected to have a good understanding of these subjects and their application in real-life scenarios.

3. General Studies Paper 2:
- The General Studies Paper 2 is the third paper in the BPSC mains exam.
- The duration for this paper is 3 hours.
- This paper focuses on Bihar-specific General Studies including topics like Bihar History, Geography, Economy, Polity, and Culture.
- Candidates are expected to have a deep knowledge of Bihar's history, geography, and socio-economic conditions.

4. Optional Subject Paper 1:
- The Optional Subject Paper 1 is the fourth paper in the BPSC mains exam.
- The duration for this paper is 3 hours.
- Candidates can choose one optional subject from a list provided by BPSC.
- The paper will be based on the chosen optional subject, and candidates are expected to have a thorough understanding of the subject.

5. Optional Subject Paper 2:
- The Optional Subject Paper 2 is the fifth paper in the BPSC mains exam.
- The duration for this paper is 3 hours.
- This paper is also based on the optional subject chosen by the candidate.
- The questions in this paper will be more advanced and in-depth compared to the previous paper.

6. General English:
- The General English paper is the last paper in the BPSC mains exam.
- The duration for this paper is 3 hours.
- Candidates are required to answer questions in English.
- This paper tests the candidate's proficiency in the English language.

In summary, the BPSC mains exam consists of six papers, each with a duration of 3 hours. The papers include General Hindi, General Studies Paper 1, General Studies Paper 2, two optional subject papers, and General English. Candidates need to allocate their time wisely to answer all the questions within the given duration.