Index and isolation level interview questions

1. What is clustered index?
2. What is non-clustered index?
3. What is unique index?
4. What is Hash index?  ( in memory OLTP)
5. What is filtered index?
6.  Index with included column
7. Clustered column-store index
8. Non-clustered column-store index
     The nonclustered index contains a copy of part or all of the rows and columns in the               underlying table. The index is defined as one or more columns of the table and has an           optional condition that filters the rows.
9. Difference between clustered column-store index vs non-clustered column-store index
     The difference is that a nonclustered index is a secondary index that's created on a                  rowstore table, but a clustered columnstore index is the primary storage for the entire            table.
10.What is a primary key, foreign key and unique key?
11. Composite index
12. covering index
13. Natural key
14.surrogate key
15. Online index.
16. Resumable online index? (yes, row-store index only for SQL 2017 and above version )
17.