Dear Olusola, 

For the first part of your question, different journals have different acceptance/rejection rates. Some journals will provide you with this information on their website while others do not. In my experience, high impact factor journals have the tendency of making this information available but this is not restricted to them.

For the second part of your question, the traditional reasons for none acceptance for publication applies here. Prominent reasons include 

• Relevance of the Manuscript to the journal
• The scientific rigour
• Anticipated impact of the work and it's relevance 
• Ethical misconduct in all its forms
• Sometimes journals will tell you they are overwhelmed with manuscripts 

Hope this is useful. 

The rejection rate mainly depends upon the ratio of total manuscripts planned for publication in a year to number of submitted manuscripts in that year. The submission rate is always increasing year by year for standard journals. Hence, the rejection rate is also increasing yearly. Because, many journals does not increase the number of issues or number of accepted papers to handle increased  submission. Open access journals may have lower rejection rate compared to traditional publishers. The reputation and journal history also contribute to rejection rate. For example, newly started journals may starve for manuscript submission. So, they reject lesser amount of manuscripts. On the other hand, a well established and reputed journals receives mammoth amount of submissions compared to allotted space. Hence the rejection rate is as high as 80-90%. For example Materials Design, Materials Characterization, Materials Science and Engineering A etc.

Please refer similar discussion in researchgate at the attached link.

https://www.researchgate.net/post/Rejection_by_Editors

There are basically two main reasons for manuscript rejection; quality of your manuscript and quality of the journal.

1. Quality of the Journal

Predatory journals may accept >90% of submissions. After all, they are more concerned about receiving your money rather than the quality of your work. You can find the acceptance rate for Elsevier and Springer journals using Journal Finder or Journal Suggestor. 

2. Quality of your Work

High quality journals have a reputation to protect and this means rejecting any paper they deem low quality or out of their scope. So, as a researcher your main focus should be translating your world-class research into a world-class manuscript. And comments above might help.