Fill up the blanks 

(a) The method of separating the seeds of paddy from its stalks is called [[1]].

(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of [[2]].

(c) Salt is obtained from seawater by the process of [[3]].

(d) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called [[4]].