Iam in desperate need of will give 40 points to whoever ! i have a quiz tomorrow but i have no idea how to do these practice problems. i know u have to use the boiling and freezing pint formula but i don't know how to plug them in because these problems all look different and asks for different things

All of the questions here are pertaining to the colligative properties of a solution and the preparation of solutions. Maybe, it would be best if you understand the equations to be used in order to answer these questions.
Freezing point depression or Boiling point elevation:

ΔT = -K (m) (i)

ΔT is the change in the freezing point or the boiling point not the freezing point/boiling point. Therefore, it should be added to the original value of the property of the solvent. 

K is a constant called the molal freezing point depression constant and for the boiling point is the boiling point elevation constant. It is a property of the solvent. 

m is the concentration of the solute in the solvent in terms of molality or kg solute/kg solvent. 

i is the vant hoff factor which will represent the number of ions which the solute dissociates when in solution.

4- c, because all matter stays the same no matter what. it is still there. 5- b, because matter is known as mass. 6-c because, flammability is a chemical property. malleability is changing the shape of an object.

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water