Which of the valence electrons of the elements below will feel the greatest shielding effect? a F
b. S
C As
d. Sn

It's a

The phase where ice changes directly to gas is called sublimation 

The question is incomplete. complete question is attached belowanswer: correct answer is option b  i.e.  solid particles  reason: filter paper has small pores, through which smaller particles can pass through. however, solid particles  have relatively larger size. hence, they are least likely to pass through.