D. A mixture
If the water is evaporating while the salt remains, it means the two are not chemically bonded and therefore are not a compound.
Answer:
A. there is an isotope of lanthanum with an atomic mass of 138.9
Explanation:
By knowing the different atomic masses of both Lanthanum atoms, we can not tell anything about their occurence in nature. Therefore, all the last three options are incorrect. Because, the atomic mass does not tell anything about the availability or natural abundance of an element.
Now, the isotopes of an element are those elements, which have same number of electrons and protons as the original element, but different number of neutrons. Therefore, they have same atomic number but, different atomic weight or atomic masses.
Hence, by looking at an elements having same atomic number, but different atomic masses, we can identify them as isotopes.
Thus, the correct option is:
<u>A. there is an isotope of lanthanum with an atomic mass of 138.9.</u>
Answer:
The concentration of the solution is 1.364 molar.
Explanation:
Volume of perchloric acid = 29.1 mL
Mass of the solution = m
Density of the solution = 1.67 g/mL
Percentage of perchloric acid in 48.597 solution :70.5 %
Mass of perchloric acid in 48.597 solution :
= 
Moles of perchloric acid = 
In 29.1 mL of solution water is added and volume was changed to 250 mL.
So, volume of the final solution = 250 mL = 0.250 L (1 mL = 0.001 L)
The concentration of the solution is 1.364 molar.
Answer:
¨molecular compounds are formed by the sharing of electrons, and ionic compounds are formed by the transfer of electrons¨
Explanation:
Answer:
True
Explanation:
The entropy of a system denoted by S is a thermodynamic function that increases in value when there are more ways to arrange the particles in the system. Some spontaneous chemical processes are entropy driven. An increase in entropy is said to drive the dissolution of ionic salts along with the evaporation of water are related to the spreading out of energy.
The entropy of a system can be taken as a measure of disorder of a system. In a spontaneous chemical process, the entropy of the universe is said to increase. ΔSunivu>0. Making the answer true.
