The correct answer to this question is "5." the oxidation number of cl in ClO3 will be a positive 5 because oxygen is naturally a -2 charge. times that by three and then account for the negative charge of the CLO3- ion.
Tearing paper, Physical Change
Answer : The metal used was iron (the specific heat capacity is
).
Explanation :
In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.


where,
= specific heat of unknown metal = ?
= specific heat of water = 
= mass of unknown metal = 150 g
= mass of water = 200 g
= final temperature of water = 
= initial temperature of unknown metal = 
= initial temperature of water = 
Now put all the given values in the above formula, we get


Form the value of specific heat of unknown metal, we conclude that the metal used in this was iron (Fe).
Therefore, the metal used was iron (the specific heat capacity is
).
To balance it, it would be N2 + 3H2 ------> 2NH3.
for c) it would be 2N2 + 6H2 -------> 4NH3
1. Relative dating
2. I don't know
3. Absolute dating
4. Absolute dating
I hope this helps...