During the Physical changes
Answer: a. two substances present; two phases present : Heterogeneous mixture
b. two substances present; one phase present
: Homogeneous mixture
c. one substance present; one phase present
: pure substance.
d. one substance present; two phases present: Heterogeneous mixture
Explanation:
A pure substance is a substance which contains definite composition of only one type of component. Hence, it cannot be separated by physical means.
Mixture is a substance which contains two or more than two types of components and they can be separated by physical means as well.
Homogeneous mixtures: It is a mixture that has uniform composition throughout the solution and the particle size or shapes are not different. There is no physical boundary between the dispersed phase and dispersion medium.
Heterogeneous mixtures: It is a mixture that has non-uniform composition throughout the solution and the particle size or shapes are also different. There is a physical boundary between the dispersed phase and dispersion medium.
Answer: The mass percent of hydrogen in ascorbic acid is 4.5 %
Explanation:
In
, there are 6 carbon atoms, 8 hydrogen atoms and 6 oxygen atoms.
To calculate the mass percent of element in a given compound, we use the formula:

Mass of hydrogen = 
Molar Mass of ascorbic acid =
Putting values in above equation, we get:

Hence, the mass percent of of hydrogen in ascorbic acid is 4.5 %.
It is A lubricant that reduces frictions creation
Taking into account the definition of molarity, the molarity of a solution prepared by dissolving 0.2 mol sucrose in enough water to make a 100 mL solution is 2
.
<h3>Definition of molarity</h3>
Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.
The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:

Molarity is expressed in units
.
<h3>Molarity in this case</h3>
In this case, you have:
- number of moles= 0.2 moles
- volume= 100 mL= 0.1 L
Replacing in the definition of molarity:

Solving:
<u><em>molarity= 2 </em></u>
Finally, the molarity of a solution prepared by dissolving 0.2 mol sucrose in enough water to make a 100 mL solution is 2
.
Learn more about molarity:
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