help me to start on this

Question

28. What causes Brownian motion?
o Brownian motion is caused by _______________ of the molecules of the dispersion medium with the small, dispersed colloidal particles. These collisions help prevent the colloidal particles from ______________.
Practice Problems
1. A gas mixture containing oxygen, nitrogen, and carbon dioxide has a total pressure of 32.9 kPa. If PO2= 6.6 kPa and PN2=23.0 kPa, what is PCO2?
2. Exactly 5.00 L of air at -50.0°C is warmed to 100.0°C. What is the new volume if the pressure remains constant?
3. List three factors that can affect gas pressure.
a. Temperature
b. Volume
c. Number of particles
4. Using three complete sentences, explain why ice is less dense than liquid water.

Answer 1

Read here for Brownian movement.
https://en.wikipedia.org/wiki/Brownian_motion

1. Ptotal = pN2 + pCO2 + pO2
2. (V1/T1) = (V2/T2) Remember to use T in kelvin.
3. Those look ok to me.
4. Go to Google and type in why is ice less dense than liquid water. Read a lot. Look especially at the Wikipedia document.