Which of the following is an example of absorption?
Silica gel, finely divided nickel and metal surface all have a porous structure which makes them good adsorbent. Thus they facilitate the adsorption process.
Therefore, (i), (iii) and (iv) are wrong options.
Calcium chloride is a strong hygroscopic substance which absorbs moisture readily. Thus, water is easily absorbed by CaCl2 making it good absorbent.
Therefore, (ii) is correct.