Answer:
= -457.9 kJ and reaction is product favored.
Explanation:
The given reaction is associated with 2 moles of 
Standard free energy change of the reaction (
) is given as:
, where T represents temperature in kelvin scale
So, 
So, for the reaction of 1.57 moles of
, 
As,
is negative therefore reaction is product favored under standard condition.
Answer: The correct option is (c). The total pressure doubles.
Solution:
Initially, only 4 moles of oxygen gas were present in the flask.
(
) ( according to Dalton's law of partial pressure)
....(1)
= Total pressure when only oxygen gas was present.
Final total pressure when 4 moles of helium gas were added:

partial pressure of oxygen in the mixture :
Since, the number of moles of oxygen remains the same, the partial pressure of oxygen will also remain the same in the mixture.

= Total pressure of the mixture.
from (1)

On rearranging, we get:

The new total pressure will be twice of initial total pressure.
Answer:
The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. The mass number is different for each different isotope of a chemical element.
Explanation:
When a solid substance is dissolved in a liquid such as water, the intermolecular forces of attraction between the molecules in the solid substance are overcome and they exist as ions in the solution. Hence the answer is 2.