When aqueous solutions of lead(ii) nitrate and potassium iodide are mixed, what is the formula for the insoluble solid (precipitate) that forms?

The formula for the precipitate is PbI₂

Explanation:

The chemical reaction is:

Pb(NO₃)₂ (aq)  +  2KI (aq)  →  2KNO₃ (aq) + PbI₂ (s)↓

All the iodides, with these cations (Ag⁺, Pb²⁺, Cu⁺, Hg²⁺, Bi⁺³ and Sn⁺⁴) produce insolubles solid.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.