Answer : The correct option is, (b) +115 J/mol.K
Explanation :
Formula used :

where,
= change in entropy
= change in enthalpy of vaporization = 40.5 kJ/mol
= boiling point temperature = 352 K
Now put all the given values in the above formula, we get:



Therefore, the standard entropy of vaporization of ethanol at its boiling point is +115 J/mol.K
The answer is B 2. As it says Atom Number of Protons and Number of Neutrons, from my understanding it means that the first number after the letter is the number of protons and the second number is the number of neutrons.
Now, If there are 6 protons in a nucleus that means there are 6 electrons on the outside, so A and D are the same element. However, you may be confused because of the different number of neutrons (6 and 7 or 7 and 8) this only means that one is and isotope of the element.
*Isotopes are atoms with the same number of protons but different number of neutrons. (Basically, same element different mass)
Answer:
I think its (B)
Explanation:
as when the air thins out at higher elevations, your lift decreases so at some point, the plane cant produce enough lift to overcome gravity.