A gas pak in an anaerobic jar
contains sodium bicarbonate
removes oxygen from the air inside the jar
induces the formation of water molecules
all of the above are true
The indicator resazurin
is pink in the absence of oxygen
is colorless in the absence of oxygen
drives off absorbed oxygen
none of the above are true
The indicator methylene blue
Is blue in an anaerobic environment
Is blue when oxygen is present
Is pink when oxygen is present
Absorbs excess oxygen
Is blue in an anaerobic environment
The correct statements are:
1. A gas pak in an anaerobic jar contains sodium bicarbonate.
2. A gas pak removes oxygen from the air inside the jar.
3. A gas pak induces the formation of water molecules.
The correct statement about the indicator resazurin is:
- It is pink in the absence of oxygen.
(The statement "is colorless in the absence of oxygen" is incorrect.)
The correct statement about the indicator methylene blue is:
- It is blue in an anaerobic environment.
To determine the correct answers, we'll need to analyze each statement and explain the logic behind them.
1. A gas pak in an anaerobic jar contains sodium bicarbonate, removes oxygen from the air inside the jar, and induces the formation of water molecules. All of the above are true.
Explanation: A gas pak in an anaerobic jar typically contains a substance like sodium bicarbonate (commonly known as baking soda) along with other chemicals. When water is added to the gas pak, it reacts with the sodium bicarbonate to produce carbon dioxide (CO2) gas. This CO2 gas then reacts with another chemical present in the gas pak, usually a metal, to form water molecules (H2O) and remove oxygen from the air inside the jar. So, all the statements mentioned are true.
2. The indicator resazurin is pink in the absence of oxygen, is colorless in the presence of oxygen, and drives off absorbed oxygen. None of the above are true.
Explanation: The indicator resazurin does change color, but its color change is opposite to what was mentioned in the statement. Resazurin is pink in the presence of oxygen and colorless in the absence of oxygen. It acts as a redox indicator and undergoes a chemical reaction in the presence of oxygen that causes it to turn pink. So, none of the statements mentioned are true.
3. The indicator methylene blue is blue in an anaerobic environment, is blue when oxygen is present, is pink when oxygen is present, and absorbs excess oxygen.
Explanation: Methylene blue is a different type of indicator compared to resazurin. It changes color depending on the presence or absence of oxygen. In an anaerobic (oxygen-free) environment, methylene blue is blue. However, when oxygen is present, it gets oxidized and turns colorless, not pink. Hence, the statement "Methylene blue is blue when oxygen is present" is incorrect. Also, methylene blue doesn't absorb excess oxygen. It is only reactive to the oxygen's presence, showing a color change based on its oxidation state.