Answer:
H₂O
Explanation:
Based electronegativity, water H₂O will have the higher melting point from the given choices. The binding force between hydrogen and oxygen is greater than for the others.
- In group 6, oxygen has the highest electronegativity.
- It pulls the shared electron closer in the bond.
- The high electronegativity between hydrogen and oxygen causes the elevated melting point between the two species.
Answer : The molarity of calcium ion on the original solution is, 0.131 M
Explanation :
The balanced chemical reaction is:

When calcium nitrate react with potassium carbonate to give calcium carbonate as a precipitate and potassium nitrate.
First we have to calculate the moles of 

Given:
Mass of
= 0.524 g
Molar mass of
= 100 g/mol

Now we have to calculate the concentration of 

Now we have to calculate the concentration of calcium ion.
As, calcium carbonate dissociate to give calcium ion and carbonate ion.

So,
Concentration of calcium ion = Concentration of
= 0.131 M
Thus, the concentration or molarity of calcium ion on the original solution is, 0.131 M
I believe its true , because when two elements form different compounds a given mass of one element will combine with the other , during any chemical change atoms arent created or destroyed they are jus rearranged