The variable is what changes during an experiment. Hopefully this helped! :)
Answer is: acid-base indicator or pH indicators.
Acid-base indicators are usually weak acids or bases and they are chemical<span> detectors for hydrogen or hydronium cations.</span>
Example for acid-base indicator is phenolphthalein (molecular formula C₂₀H₁₄O₄). Phenolphthalein is <span>colorless in </span>acidic<span> solutions and pink in </span>basic<span> solutions.
Another example is m</span><span>ethyl orange. It is red colour in acidic solutions and yellow colour in basic solutions.</span>
Temperature is a measurement of average kinetic energy of the particles in a sample which means that the sample with the highest temperature has the highest average kinetic energy of the particles.
That being said the answer would be 4) 10 mL of H2O (l) at 35 degrees Celsius since that sample has the largest temperature.
I hope this helps. Let me know if anything is unclear.
%C= 12/12 + 2·16=0,273=27,3%.
