<span>A. the number of perching birds present</span>
Answer : Phenolphthalein is pink in an aqueous solution having a ph of 12.
Explanation :
Phenolphthalein is an acid-base indicator. It is a colorless solution which remains colorless in acidic solution and changes to pink in basic solution.
An acidic solution has a pH of less than 7 whereas a basic solution has a pH of greater than 7.
The pH transition range for phenolphthalein is between 8-10. Than means when the pH is greater than 8, the color of the solution starts to change.
Among the given options, the only option that shows a basic solution is option (4) . Therefore we can say that phenolphthalein would be pink in a solution having a pH of 12.
Recycling!! And also planting more trees.
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Only CH4 is covalently bonded. All other compounds are ionic compounds.
So A is the answer.
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I think the correct answer from the choices listed above is option C. The tools that <span>should be used to record the most complete data about a gas are a manometer and a thermometer. Pressure and temperature are important measurements for a gas since from these data we can calculate any other properties of the gas.</span>