Can someone answer these THREE questions?

1.) Jenny wants to determine if a new brand name washing detergent is better than her old detergent. She washes ten dirty t-shirts with the new washing detergent and ten dirty t-shirts with the old detergent. Identify the dependent and independent variables for this experiment.

2. ) Ronald wants to see if a new shower cleaner works better in removing soap scum than his old cleaner.  He pumps 50 sprays on one half of the shower and pumps 50 sprays of his old cleaner on the other half. Identify the constant in this experiment.

3.) A solid is cooled to a very low temperature. Assuming the mass remains constant, how, if at all, does this affect the density of the solid?