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 
Kinetic energy is when an object is in motion
How I got my answer is really easy you simply just look at the answers and see which one says the object is in motion . Your answer would most likely be D
Method:
1) Find the atomic number in a periodic table: the number of electrons equal the atomic number
2) Use Aufbau rule
Element atomic number electron configuration
<span>
P 15 1s2 2s2 2p6 3s2 3p3
Ca 20 </span><span><span>1s2 2s2 2p6 3s2 3p6 4s2
</span>Si 14</span><span> 1s2 2s2 2p6 3s2 3p2
S 16</span><span><span> 1s2 2s2 2p6 3s2 3p4
</span>Ga 31. </span><span><span> 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p</span> </span>
Answer:
[NH₃] = 14.7 mol/L
Explanation:
28 wt% is a type of concentration that indicates that 28 g of ammonia is contained in 100 g of solution.
Let's determine the amount of ammonia:
28 g . 1 mol / 17.03g = 1.64 moles of NH₃
You need to consider that, when you have density's data it is always referred to solution:
Mass of solution is 100 g, let's find out the volume
0.90 g/mL = 100 g /V
V = 100 g / 0.90mL/g → 111.1 mL
We convert the volume to L → 111.1 mL . 1 L/1000mL = 0.1111 L
mol/L = 1.64 mol/0.1111L → 14.7 M
mol/L = M → molarity a sort of concentration that indicates the moles of solute in 1L of solution
The alloy has a density of 21.186g/cc. So for a kilogram or 1000 grams/21.186 g/cc= 45.7 cc. So the answer is 45.7 cc of the allow to make up a kilogram which shows that the density of the allow can be used to calculate the volume of a larger mass ie the kilogram.
