Answer:
600k
Explanation:
In this problem, we need to use a gas law that relates temperature to volume. The gas law to use here is the Charles’ law.
The Charles’ law posits that temperature and volume are directly proportional, provided that the pressure is kept constant.
Mathematically:
V1/T1 = V2/T2
We are looking at getting V2, hence we can write the mathematical equation as:
T2 = V2T1/V1
Asides the fact that we know that the gas is monoatomic, we do not know its volume. Let its initial volume be v. Since it expanded adiabatically, this means that its new volume is 2v
Hence: V1 = v , V2 = 2v , T1 = 300k and T2 is ?
Substituting these values, we have the following:
T2 = (2v * 300)/v
T2 = 600k
Heat gained in a system can be calculated by multiplying the given mass to the specific heat capacity of the substance and the temperature difference. It is expressed as follows:
Heat = mC(T2-T1)
Heat = 5(0.90)(32.1 - 22.1)
Heat = 45 J energy gained
Stirring affects how quickly a solute dissolves in a solvent, but has no effect on how much solute will dissolve. The amount of solute that will dissolve is affected by temperature - more will dissolve at higher temperatures. This is called the solubility of the solute
Answer: Neon
Explanation: The second period involves elements with n =2 i.e. the elements have electrons in second shell. The element with filled s and p orbitals will have outer electronic configuration 
Thus the element with filled orbital will be a noble gas. It will have total of 10 electrons and the element will be neon with complete outer electronic configuration will be:

There is 18 + 633= 651 grams of HCl in aqueous form depending how the reaction is done