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 
Answer:
The value of Kp at this temperature is 7.44*10⁻³
Explanation:
Chemical equilibrium is established when there are two opposite reactions that take place simultaneously at the same speed.
For the general chemical equation for a homogeneous gas phase system:
aA + bB ⇔ cC + dD
where a, b, c and d are the stoichiometric coefficients of compounds A, B, C and D, the equilibrium constant Kp is determined by the following expression:

Where Px is the partial pressure of each of the components once equilibrium has been reached and they are expressed in atmospheres. The equilibrium constant Kp depends solely on temperature and is dimensionless.
In the case of the reaction:
2 HI (g) ⇔ H₂ (g) + I₂ (g)
the equilibrium constant Kp is determined by the following expression:

The system comes to equilibrium at 425 °C, and
- PHI = 0.794 atm
- PH2 = 0.0685 atm
- PI2 = 0.0685 atm
Replacing:

Kp=7.44*10⁻³
<u><em>The value of Kp at this temperature is 7.44*10⁻³</em></u>
Answer: n=15.56moles
Explanation:
PV = nRT
where
P is pressure in atmospheres
V is volume in Liters
n is the number of moles of the gas
R is the ideal gas constant = given as (0.0821L -atm/k-mol
PV = nRT
n= PV/RT
n= (1.5 X 230)/ (0.0821 X 270)
n= 15.56 moles
Answer:
Oxygen is the most contain in earth but you asked in a,b,c and d. So I'll choice A. aluminium.
To answer this question a balanced chemical equation is necessary. The correct equation is: N2 + 3H2 = 2NH3
From this equation, one mole of nitrogen react with 3 moles of hydrogen to give 2 moles of ammonia.
Therefore, the mole ratio of NH3 to N2 is 2:1