C. in the reaction of copper and silver nitrate, a new substance appeared in the test tube. describe the physical appearance of the substance and identify its chemical formula

Cu(s) + 2AgNO₃(aq) = Cu(NO₃)₂(aq) + 2Ag(s)

The solution of copper(II) nitrate and metallic silver formed in the reaction. 

Colourless solution becomes blue due to the formation of the copper (II) aquacomplex.

Cu²⁺ + 4H₂O = [Cu(H₂O)₄]²⁺
                            blue

Ch4 is nonpolar and insoluble in water. since all of the hydrogen atoms are evenly spread around the carbon atom even through the c h bond is polar all the poles cancel each other out.