[CIE alevel]

HERES THE QUESTION: http://i34.tinypic.com/2md4a5l.jpg

Heres what i think so far:
a) (i) Other 2 independent variable: Ambient temperature  and  Size of CaCO3 marble chips
   (ii) Dependent variable: volume of CO2 gas evolved
**Please further explain what is really meant by independent & dependent  variable...??**
b) Hypothesis: As the concentration of HCl acid is increased the rate of reaction will also increase

Now, how is part c)  done??
My diagram is something like this:


Am I using proper appartus ??

In: (c)     
 (i) description of  procedures....do i need to give order of assembling the things in diagram?? If not then what r the procedures to be written??
 
(ii) & (iii)  how to measure and accurately vary concentration of HCl (i.e.independent variable) I Think the HCl acid needs to be diluted...but how to explain it?? How can i use given 11 mol/dm^3 ??

 (iv) do i just mention that i used electric  heater to control temperature of reaction  & that  i keep same size & number of chips???

 (v) safety precautions: Take care when using corrosive conc. HCl to make dillute HCl.
*** Is this right**

 (vi) **no idea here**


Please reply with full explantions and help me with the doubtful questions.     

[CIE alevel]

Can some1 please reply to this urgently!!???

[CIE alevel]

Any inputs??? Is this unanswerable??

[billnotgatez]

I used Google

independent & dependent variable

and got many answers like this one

http://www.uncp.edu/home/collierw/ivdv.htm


I assume similar information is in your textbook

[billnotgatez]

I used Google

chemistry lab precautions

and got many answers like this one

http://www.sciencebyjones.com/safety_rules.htm

you might select appropriate items from this list or others

[billnotgatez]

I assume there are many variables that can be modified and I assume that temperature is one of them. It can also be held constant and other variables manipulated.