please help.

6. Hashing. a. What is Hashing? What is a hash function? b. Why does twitter use hash tags? c. What is Collision? Cite two ways to deal with collisions. d. Consider the following hash function: Compute the addresses of the following keys: 1288, 1847, 8719, 8991,814,1777. In case of collision, explain where to put the second key using each policy cited in question (c). e. NJIT student ID's are 8-digit integers, and NJIT has about 12000 students. Design a hashing mechanism for storing student records using student ID's as the key