4 moles of hydrogen = 4 * 1.008 = 4.032 grams
1 mole of helium = 4.003 grams
Difference is 4.032 - 4.003
= 0.029 g
Answer: The entropy change of the surroundings will be -17.7 J/K mol.
Explanation: The enthalpy of vapourization for 1 mole of acetone is 31.3 kJ/mol
Amount of Acetone given = 10.8 g
Number of moles is calculated by using the formula:
Molar mass of acetone = 58 g/mol
Number of moles = 
If 1 mole of acetone has 32.3 kJ/mol of enthalpy, then
0.1862 moles will have = 
To calculate the entropy change for the system, we use the formula:
Temperature = 56.2°C = (273 + 56.2)K = 329.2K
Putting values in above equation, we get
(Conversion Factor: 1 kJ = 1000J)
At Boiling point, the liquid phase and gaseous phase of acetone are in equilibrium. Hence,
Answer:
C. Gain in electron(s) resulting in a decrease of oxidation number.
Explanation:
Redox reactions are reactions involving transfer of of electron between two species (reduction specie) and (oxidation species) and change resulting in change in oxidation number.
Reduction in terms of redox reaction is the specie that accepts electron(s) and gets "reduced" since its oxidation state has been reduced.
For example
Cl + e- → Cl⁻
The above reaction is an example of reduction reaction taking place in a redox reaction. We can see that Chlorine oxidation state was changed from (0) to (-1) state.
The correct answer among the choices given is option B. The one that describes a proper use of eyeglasses is that using diverging lenses to help a nearsighted person by moving the image from in front of the retina to the retina. For this, t<span>he lenses will diverge the light before it reach the eye and aim it to the retina, correcting our nearsighted visual.</span>
