my independent, dependent and controlled variables!!

idea number 1: the affect of temperature on the elasticity of a rubber band
independent variable: temperature and thickness of rubber band
dependent variable: elasticity of the rubber band
controlled variables: time, 'brand' of rubber band and measuring tool(ruler)

idea number 2: does temperature affect density
independent variable: temperature and liquids of different densities(water, oil, etc)
dependent variable: density- will it float or sink
controlled variables: time, container, object and volume of liquid

idea number 3: what type of acid has the most effect on egg shells
independent variable: acid (vinegar, orange juice, etc)
dependent variable: effect on the egg shell- how thin/hard the egg shell will be
controlled variables: time, container, volume of acids and 'brand' of eggs

idea number 4: what type of solution best protects egg shells from acids
independent variable: solution (Listerine, toothpaste, etc) and sugar-acid drinks
dependent variable: effect on the egg shell- if the egg shell has changed(in term of colour, thickness of shell,etc)
controlled variables: time, container, volume of solutions/acids and 'brand' of egg, ,

idea number 5: what solvents will remove permanent marker ink best
independent variable: solvents (water, alcohol, vinegar, etc) and permanent marker pens
dependent variable: removal of permanent marker ink
controlled variables: time, container, volume of solvents, area of ink spot and piece of plastic


PS. i find it really ridiculous that, just because i can't make up my mind about what to do, i have to do this for all the ideas i have for the experiment :(

it would be greatly appreciated if anyone can help me narrow down the options

Thankyou!! :)