Answer:
I believe 11 is B 12 is C 13 is B and 14 is C
You first need to write the balanced chemical reaction for what is going on.
Ca(OH)₂+2HCl→2H₂O+CaCl₂
After you make the balanced chemical reaction, First you find the moles of HCl used. To do this multiply 0.0375L by 0.124M to get 0.00465mol HCl. Then you multiply 0.00465mol HCl by (1mol Ca(OH)₂)/(2mol HCl) to get 0.002325mol Ca(OH)₂. Finally to find concentration of Ca(OH)₂ used you divide 0.002325mol by 0.020L to get 0.116M Ca(OH)₂.
Therefore the concentration of the unknown solution of Ca(OH)₂ was 0.116M.
I hope this helps. Let me know if anything is unclear.
The state of the substance, most likely, would be a gas. Given the same amount of the substance being able to fill different volumes of containers, means that the substance is compressible. From the three phases of matter, gas is surely the compressible one while liquids are sometimes compressible but only up to certain extent. Also, the substance cannot be a a solid since a solid would have a definite shape and volume. Nor it cannot be a liquid since a liquid cannot fill the whole container and it does not change its volume no matter what is the container.
4CO2 is 4 molecules of CO2. CO2 consists of one carbon atom and two oxygen atoms.
