Answer: Option (E) is the correct answer.
Explanation:
A spontaneous reaction is defined as the process which tends to occur on its own. And, a non-spontaneous reaction is defined as a process for the completion of which we have to provide certain conditions.
For example, ice melting at 
is spontaneous primarily due to the increase in molecular disorder (dispersal of matter). Also, melting of ice is taking place on its own without any external force.
It is not necessary that all exothermic reactions will be exothermic in nature.
Thus, we can conclude that the statement all exothermic reactions are spontaneous, is false.
Answer:
24.09 grams of chlorine gas reacted.
Explanation:
Moles of sodium chloride = 
According to reaction, 2 moles of NaCl are formed from 1 mole chlorine gas.
Then 0.6786 moles of NaCl will be formed from;
Mass of 0.3393 moles of chlorine gas:
0.3393 mol × 71 g/mol = 24.09 g
24.09 grams of chlorine gas reacted.
The given question is incomplete. The complete question is:What is the relative atomic mass of a hypothetical element that consists isotopes in the indicated natural abundances.
Isotope mass amu Relative abundance
1 77.9 14.4
2 81.9 14.3
3 85.9 71.3
Express your answer to three significant figures and include the appropriate units.
Answer: 84.2 amu
Explanation:
Mass of isotope 1 = 77.9
% abundance of isotope 1 = 14.4% = 
Mass of isotope 2 = 81.9
% abundance of isotope 2 = 14.3% = 
Mass of isotope 3 = 85.9
% abundance of isotope 2 = 71.3% = 
Formula used for average atomic mass of an element :
![A=\sum[(77.9\times 0.144)+(81.9\times 0.143)+(85.9\times 0.713)]](https://tex.z-dn.net/?f=A%3D%5Csum%5B%2877.9%5Ctimes%200.144%29%2B%2881.9%5Ctimes%200.143%29%2B%2885.9%5Ctimes%200.713%29%5D)
Therefore, the average atomic mass of a hypothetical element that consists isotopes in the indicated natural abundances is 84.2 amu
1,38×10²² = 0,138×10²³
0,138×10²³ ----- 1,5g
6,02×10²³ ------ X
X = (1.5×6,02×10²³)/0,138×10²³
X = 65,435 g/mol
It's ZINC (Zn)
:•)
