Answer : The initial temperature of system 2 is, 
Explanation :
In this problem we assumed that the total energy of the combined systems remains constant.
The mass remains same.
where,
= heat capacity of system 1 = 19.9 J/mole.K
= heat capacity of system 2 = 28.2 J/mole.K
= final temperature of system = 
= initial temperature of system 1 = 
= initial temperature of system 2 = ?
Now put all the given values in the above formula, we get
Therefore, the initial temperature of system 2 is,
3.6 x 10^-4
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The answer & explanation for this question is given in the attachment below.
Volume is the amount of space the matter takes up, density is mass OF the volume
