Answer: A closed system, because energy can enter or leave the container, but the water molecules cannot
Explanation:
Open system: In this system energy and matter both have access to their surroundings beyond the boundaries of system. .
Closed system :In this type system only energy has an access to its surroundings beyond the boundaries of system but not matter.
Isolated system:In this type system exchange of both energy and matter are restricted to move outside the boundaries of system.
According to question, the system given is a closed system because energy is transferred from the burner to glass flask and from the glass flask to the water (matter). But water molecules are only getting condensed on the inside surface of the flask that is exchange of matter beyond the boundaries of the system is restricted. Hence, closed system ,A closed system, because energy can enter or leave the container, but the water molecules cannot.
Answer:
a colloid and a solution
Explanation:
When solute particles completely dissolve in a solvent, a true solution is formed. The solute particles in this case are so little that they can not be seen with naked eyes. A true solution does not scatter rays of light.
In a false solution, the solute particles are larger than the solute particles in true solutions but are not large enough to be seen with naked eyes. False solutions scatter rays of light. False solutions are also called colloids.
The major difference between a solution and a colloid is that colloids scatter light rays (Tyndall effect) while a true solution does not scatter light rays.
Answer:

Explanation:
Conversion problems could be solved using dimensional analysis for convenient use and understanding. Dimensional analysis is a technique of multiplying the measure we have by a fraction corresponding to some two equal measures in different units.
In order to apply dimensional analysis here, we firstly need to know that a prefix 'n' stands for 'nano', and nano means
. In this case, we have nanoliters. Using the prefix, we can find a relationship between nanoliter and liter:

We may now apply dimensional analysis. Since we wish to convert into liters, we'll be multiplying the number we have in nL by a fraction that contains this relationship with liters in the numerator and nanoliters in the denominator, so that nL terms cancel out and we would obtain the final answer in liters:

Answer;
C) The solid has bubbles forming on its surface.
Explanation;
-Chemical reactions involves the reaction of reactants that involves rearrangement of their structure resulting to the formation of new substances.
-There are a number of common indicators that are used to show that a chemical reaction has taken place, namely;
- Change of color
- Change of Odor
- Change in temperature or energy
- Formation of precipitate
- Effervescence or formation of gas bubbles.
Answer:
An energy pyramid shows the flow of energy at each trophic level in an ecosystem. A pyramid shape is used because energy is lost at each trophic level when organisms use it up.
Explanation: