Answer:

Explanation:
1. Convert decagrams to grams

2. Convert grams to decigrams
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Answer is: a) in the presence of a base.
Phenolphthalein is colorless in acidic solutions and pink in basic solutions.
Acid-base indicators are usually weak acids or bases and they are chemical detectors for hydrogen or hydronium cations.
Example for acid-base indicator is phenolphthalein (molecular formula C₂₀H₁₄O₄).
When solution turns phenolphthalein pink, it means it is basic (pH>7).
Unsaturated organic compounds with a carbon-to-carbon double bond and alkynes with a carbon-to-carbon triple bond, as well as aldehydes and ketones with a carbon-to-oxygen double bond, undergo addition reactions.