Operating system security 2

Please write a paragraph each for each of the following questions
1.    In short sentences describe the two security goals.

2.    Name and briefly describe the three elements of security policy.

3.    What is the difference between access control list and capability list.

4.    Write short note on the following access control policies
a.    DAC, MAC, RBAC and ABAC

5.    Why does modern OS separate virtual memory into kernel space and user space?