Phenolphthalein<span> is often used as an indicator in acid–base titrations. For this application, it </span>turns<span> colorless in acidic solutions and </span>pink<span> in basic solutions. </span>Phenolphthalein<span> is slightly soluble in water and usually is dissolved in alcohols for use in experiments.
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The following is produced when propane (C₃H₈) is combusted completely : H₂O
<h3>Further explanation </h3>
Complete combustion of Hydrocarbons with Oxygen will be obtained by CO₂ and H₂O compounds.
If O₂ is insufficient there will be incomplete combustion produced by CO and H and O
Hydrocarbon combustion reactions (especially alkanes) 
For combustion of propane C₃H₈ (n = 3) ⇒ completely(excess O₂) :
C₃H₈+5O₂⇒3CO₂+4H₂O
The products of combustion : CO₂ and H₂O
Answer:
E. potassium (K) and bromine (Br)
Explanation:
An ionic bond is formed between compounds with a large electronegativity difference between them. It is usually between a metal and non-metal.
- Potassium is a true metal found in group 1 on the periodic table.
- Bromine is a highly electronegative non-metal which is a halogen.
- Potassium will lose one of its electrons which will be gained by the Bromine.
- The electrostatic attraction between the two species will cause the ionic bond to form.
- The ability of one specie willing to lose electron and the other gaining, is the main bed rock of ionic bonding.
The number of years that must be invested at a rate of 7 % to earn$ 303.52 in interest is
8 years
<em><u>calculation</u></em>
- <em><u> </u></em><em>by use of the formula A = P (1+ rt) </em>
- <em> where : A is the final amount = 542 + 303.52 =$ 845.52</em>
<em> P is the principal money to be invested = $ 542</em>
<em> r= rate= 7/100=0.07</em>
<em> t= time required</em>
<em>=$ 845.52=$ 542( 1+ 0.07 t)</em>
- <em>open the bracket</em>
- <em>= $845.53= $542 + $37.94 t</em>
- <em>like terms together</em>
=$ 845.53 -$542 = $37.94 t
=$303.52 =$37.94 t
- divide both side by $37.94
= $303.52/ $ 37.94 = $37.94t/$37.94
t= 8 years
Answer:
Changing the pendulum design after the first trial was an example of <u>evaluating the model</u> to solve the problem presented by the teacher.
Explanation:
A model constitutes an abstract representation of a certain aspect of reality, and has a structure that is formed by the elements that characterize the aspect of the modeled reality and by the relationships between these elements.
This achieved result provides a better understanding of the problem being studied, offering aspects that can be changed or improved to solve the problem posed, obtaining more information about the reality of the phenomenon that is being represented.