We will assume helium to behave as an ideal gas and apply the ideal gas law:
PV = nRT
For pressure measured in atmospheres and volume measured in liters, the value of the molar gas constant is 0.082. Therefore:
T = PV / nR
T = (2.57 x 15.5) / (1.2 x 0.082)
T = 404.8 Kelvin
Molecules may be similar or different on the basis of size, shape, structure and chemical composition.
<h2>Similarities and differences</h2>
Two molecules can be considered similar or different on the basis of size, shape, structure and chemical composition. The molecules in the two proposed systems are consider the same when they are similar in size, shapes, structure and chemical composition.
While on the other hand, the molecules is considered different when they have different structure and chemical composition so we can say that molecules may be similar or different on the basis of size, shape, structure and chemical composition.
Learn more about molecules here: brainly.com/question/26044300
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Lets take a moment to list all the characteristics of the group 18 (also known as noble gases and/or group 8) elements:
- They have 8 valence electrons.
- Don't need ANY more electrons because their octet is full (stable).
- Are stable
- Not reactive
- Known as the noble gases
Now.. lets take some time to think about why elements want to form ions:
Elements form ions to either gain or lose valence electrons to the element they bond with. This helps them GAIN a full octet. What is a full octet, you may ask? An octet is when an element has all 8 valence electrons and is stable, making it nonreactive.
Why would an element with a full octet want to bond? It already has a full octet, it does not need to bond.
That, my fellow Brainly user, is why the noble gases do not need to bond.
I really do hope this helps! Enjoy, and good luck on the studies.
Answer:
The answer is D) all of the above
Explanation:
This is because if something has mass then it is composed of matter.
Can I have brainliest please?
Answer: 1. 
increases.
Explanation:
Any change in the equilibrium is studied on the basis of Le-Chatelier's principle.This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.
For the given equation:
If the concentration of 
is increased , according to the Le-Chatlier's principle, the reaction has to shift to right or forward direction. In order to do that the concentration of products has to increase.
Thus the concentration of increases.
