Answer: I disagree. Elements form all pure substances, but some pure substances include elements bonded together to form molecules and compounds.
Explanation:
Pure substances are those that have a uniform and constant (invariable) composition.
That condition is met by both elements and compounds.
Elements are pure substances of one only kind of atoms. For example, gold, oxygen, sodium, hydrogen, are pure substances that arer elements. There are 118 elements known and they are all listed in the periodic table.
Compounds are pure substances formed by two or more different kind of atoms. Water (H₂O), table salt (NaCl), and ethanol (CH₃-CH₂OH), are examples of pure substances that are compounds. There are pratically infinite different compounds.
In conclusion, compounds are also pure substances, since every sample of a given compound has always the same kind of elements bonded in the same way.
Answer: This image is the answer to this question.
Explanation:
You would observe, trying to identify if there's a minimum difference in each beaker. Like, colour, or using an <em>bagueta </em>(idk how to say it in english), churning it or something like that.
A system is a part of the <em>physical</em> universe defined <em>arbitrarily</em> for observation purposes.
Boundaries are a part of the <em>physical</em> universe that are around the system.
In a scientific sense, a system is a part of the <em>physical</em> universe whose boundaries, that is, the limit between the system and its surroundings, are defined <em>arbitrarily</em> for observation purposes.
A system contains at least a model, represented in a phenomenological way, and it can be isolated (no mass nor energy interactions), closed (no mass interactions) or open.
The surroundings are a part of the <em>physical</em> universe that are around the system.
An example is a coffee-maker, where coffee-maker the system and air represents the surroundings, the coffee-maker receives energy from a heat source to warm up itself and releases part of such energy to the air.
We kindly invite to check this question on systems and surroundings: brainly.com/question/6044762
Answer : The volume of water added are, 15 mL
Explanation :
Formula used :

where,
are the initial molarity and volume of HCl.
are the final molarity and volume of water.
We are given:

Putting values in above equation, we get:

Hence, the volume of water added are, 15 mL