It is not directly over a flame because it depends on the substance you might not want to heat it too much.you never know what could happen
The moles of gas in the bottle has been 0.021 mol.
The ideal gas has been given as the gas where there has been negligible amount of interatomic collisions. The ideal gas equation has been given as:

<h3>Computation for the moles of gas</h3>
The gi<em>ve</em>n gas has standard pressure, 
The volume of the gas has been, 
The temperature of the gas has been, 
Substituting the values for the moles of gas, <em>n:</em>
<em />
<em />
The moles of gas in the bottle has been 0.021 mol.
Learn more about ideal gas, here:
brainly.com/question/8711877
Potassium oxide has the antifluorite structure. The antifluorite structure have compounds with the stoichiometry X₂Y, where X is the cation and Y is the anion. In the antifluorite structure <span>positions of the </span>cations<span> and </span>anions<span> are reversed relative to their positions in calcium fluoride.</span>
Potassium ions coordinated to 4 oxide ions, <span>potassium ions are all in the tetrahedral holes.</span>
Answer:
occur if two of the ions form an insoluble ionic compound, which precipitates out of solution
Explanation:
When two ionic compounds are dissolved in water, a double replacement reaction takes place if two of the ions form an insoluble ionic compound, which precipitates out of solution. In double displacement reaction ions switch partners. And hence, produce an insoluble precipitate.
Answer:
Option (D)
Explanation:
The super-heating is usually defined as a phenomenon where a certain amount of energy is needed to raise the temperature of the water vapor beyond its normal saturation point. This is also known as the boiling delay.
The super-heat can be mathematically written as:
Super-heat = Current temperature - Boiling point of the liquid.
Thus, super-heat refers to the amount of energy that is required to increase the temperature of vapor beyond its point of saturation.
This super-heat is essential as it helps in preventing the damages of machines like air conditioner, fridge and also helps in their soft running.
Hence, the correct answer is option (D).