frozen list as partition key in Cassandra is a good practice or any alternates

Question

I have created a table & primary key type is set.

CREATE TABLE IF NOT EXISTS keyspace1.list_by_account 
    (id uuid, name text,
     account frozen <set<text>>, 
     PRIMARY KEY (account, id));

is this a good way to find later on entries from it?

Below query will scan all partitions or will directly find partitions on base of IN parameters?

SELECT * FROM keyspace1.list_by_account WHERE account IN ? 

Last thing when I run below query, this does not return any data:

SELECT * FROM keyspace1.list_by_account WHERE account CONTAINS 'private_account1';

Currently I am using Cassandra 2.1.14.