The purpose of studying a system is to identify the strengths and weaknesses of the existing system and examine current inputs, outputs, processes, security and controls, and system performance.

The purpose of system is to make system more reliable and efficient for desired work completion

Explanation:

In most of the times, the system analysts operate in a dynamic environment where change is  the necessary process . A business application, a business firm or a computer system may be the required environment. In order To rebuild a system, the key elements must be considered which we need to examine are as follows:

1. Outputs and inputs.

2. Security and Control.

3. processor

4. Environment.

5. Feedback.

6. Boundaries and interface.

b) phosphorus pentoxide

reserve is the answer