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, 
VSEPR theory , Valence bond theory and Molecular Orbital Theory
The mass of a tree is primarily carbon. The carbon comes from carbon dioxide used during photosynthesis. During photosynthesis, plants convert the sun's energy into chemical energy which is captured within the bonds of carbon molecules built from atmospheric carbon dioxide and water.
Answer:
Na + H₂O → NaOH + 1/2 H₂
Explanation:
When sodium reacts with water, it forms sodium hydroxide and molecular hydrogen. The unbalanced equation is:
Na + H₂O → NaOH + H₂
We have to balance this equation so it obeys the law of conservation of mass. We have 1 atom of Na on each side and 1 atom of O on each side, so these elements are balanced. However, we have 2 atoms of H on the left side and 3 atoms of H on the right side. The easiest way to balance the H without modifying the other elements is by making 1/2 the stoichiometric coefficient of H₂.
Na + H₂O → NaOH + 1/2 H₂