Answer : The specific heat of metal 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 metal = ?
= specific heat of water = 
= mass of metal = 129.00 g
= mass of water = 45.00 g
= final temperature = 
= initial temperature of metal = 
= initial temperature of water = 
Now put all the given values in the above formula, we get


Therefore, the specific heat of metal is
.
Alkaline earth metal are the elements present in II group in the periodic table and are known as 'Metals' and have a charge of +2.
Alkaline earth metals - Be , Mg Ca, Sr , Ba, Ra
Halogens are present in VII A group in the periodic table and are 'Non-metals' and have a charge of -1.
Halogens - F, Cl, Br, I, At
When Alkaline earth metal (metals) combine with Halogens (non-metals) the compound formed will be ionic compound and the formula of the compound will be based on the charges of the element.
When we write the formula of the ionic compound the charges of the elements get criss crossed.
For example - Mg (Alkaline earth metal) have a charge of +2 and Cl (Halogen) have a charge of -1 and when they combine to form the formula their charges get criss crossed and we will get
or 
When an alkaline earth metal, A, reacts with a halogen, X, the formula of the Ionic compound formed should be 
An element with 8 valence electrons is Neon (Ne).
Ps: Any element under group 18 has 8 valence electrons except for Helium (He).