Can you show me the atoms please? I would be able to help.
Answer:
Radioactive isotopes ranging from 11O to 26O have also been characterized, all short-lived. The longest-lived radioisotope is 15O with a half-life of 122.24 seconds, while the shortest-lived isotope is 12O with a half-life of 580(30)×10−24 seconds (the half-life of the unbound 11O is still unknown).
An acid-base indicator is used to identify the presence of an acid or base. These indicators exhibit different colors depending on the solution that they are in. They are especially useful when completing titrations to determine the molarity of an unknown substance and is denoted as option D.
<h3>What is Titration?</h3>
This is done in the laboratory and involves the slow addition of one solution of a known concentration to a known volume of another solution of unknown concentration.
Acid-base indicators are used to determine the presence of an acid or base in a solution which is based on the colors seen when performing the chemical reaction.
It is used to calculate the the molarity of an unknown substance through the knowledge of the other parameters which is therefore the reason why option D was chosen as the most appropriate choice.
Read more Acid-base indicators here brainly.com/question/2815636
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Explanation:
- Evaporation is defined as a process in which liquid state of water is changing into vapor state.
So, we need to break the bonds of liquid substance in order to convert it into vapor state. And, energy is absorbed for breaking of bonds which means that evaporation is an endothermic process.
Hence, the statement evaporation of water is an exothermic process is false.
- When a hydrocarbon reacts with oxygen and leads to the formation of carbon dioxide and water then this type of reaction is known as combustion reaction.
A combustion reaction will always release heat energy. Hence, combustion reaction is exothermic in nature.
- When energy is transferred as heat from the surroundings to the system then it means energy is being absorbed by the system. And, absorption of heat is an endothermic process for which
is positive.
- Whereas when energy is transferred from system to the surrounding then it means energy is released by the system which is an exothermic process.
Hence, for an exothermic process value of
is negative.
Thus, we can conclude that statements which are true are as follows.
- A combustion reaction is exothermic.
- When energy is transferred as heat from the system to the surroundings,
is negative.
- For an endothermic reaction Deta H is positive.