[Part A already answered, just for reference.] Please help with Part b a) In Linux, the password hash is produced by app

[answerhappygod]

[Part A already answered, just for reference.] Please
help with Part b
a) In Linux, the password hash is produced by applying a hash
function for many rounds (e.g., 5000 rounds for SHA-512). This
seems to waste time, why does Linux do this? (5 points)
b) Currently, the salt used in the shadow file is saved in the
file in plaintext. Isn’t it better not to save the salt in
plaintext? Please explain. (5 points)