A biochemist needs a medium for acid-producing bacteria. The pH of the medium must not change by more than 0.05 pH units for every 0.0010 mol of H3O+ generated by the organisms per liter of medium. A buffer consisting of 0.10 M HA and 0.10 M A- is included in the medium to control its pH. What volume of this buffer must be included in 1.0 L of medium?

Yes you are correct use the scientific method

Sorry i dont understand the question can you rephase it?

Vander waals forces are inter molecular bonds that exist within molecules of the same substance. a water molecule is made up of oxygen and hydrogen atoms which share electrons between each other. the vander waals forces are forces that exist between multitude of different  molecules of water. dipole dipole forces is the type of vander waals force that exist in water. the oxygen atom which is more electronegative pulls the shared electron closer to itself thus generating a partial negative charge while the hydrogen acquire a partial positive charge. these two different charges causes attraction to occur in water molecules.

The answer is the third option extremely gradual