How can you tell that a precipitate has formed?

What phase of matter has particles that are held together but can flow past each other and takes the shape of a container, filling it from the bottom up?

Using a value of ksp = 1.8 x 10-2 for the reaction pbcl2 pb+2(aq) + 2cl -(aq). if the value of ksp was determined to be only 1.2 x 10-2: too much solid has dissolved. additional precipitate is forming. the solution is unsaturated. the ions are now combining to reduce their concentrations.

Write the chemical formula for a compound that is made of an element from group 1 and an element from group 17