Answer:
The standard heat of formation of Compound X at 25°C is -3095.75 kJ/mol.
Explanation:
Mass of compound X = 7.00 g
Moles of compound X = 
Mass of water in calorimeter ,m= 35.00 kg = 35000 g
Change in temperature of the water in calorimeter = ΔT
ΔT = 2.113°C
Specific heat capacity of water ,c= 4.186 J/g °C
Q = m × c × ΔT

Heat gained by 35 kg of water is equal to the heat released on burning of 0.100 moles of compound X.
Heat of formation of Compound X at 25°C:

= -3095.75 kJ/mol
Answer:
No, it is not.
Explanation:
Most solutions do not behave ideally. Designating two volatile substances as A and B, we can consider the following two cases:
Case 1: If the intermolecular forces between A and B molecules are weaker than those between A molecules and between B molecules, then there is a greater tendency for these molecules to leave the solution than in the case of an ideal solution. Consequently, the vapor pressure of the solution is greater than the sum of the vapor pressures as predicted by Raoult’s law for the same concentration. This behavior gives rise to the positive deviation.
Case 2: If A molecules attract B molecules more strongly than they do their own kind, the vapor pressure of the solution is less than the sum of the vapor pressures as predicted by Raoult’s law. Here we have a negative deviation.
The benzene/toluene system is an exception, since that solution behaves ideally.
Explanation:
For AX type ceramic material, the number of formula per unit cells is as follows.

or, 
where, n' = no. of formula units per cell
= molecular weight of cation = 90.5 g/mol
= molecular weight of anion = 37.3 g/mol
= volume of cubic cell = 3.55
a = edge length of unit cell = 
= Avogadro's number = 
= density = 3.55 
Now, putting the given values into the above formula as follows.

= 
= 0.9
= 1 (approx)
Therefore, we can conclude that out of the given options crystal structure of cesium chloride is possible for this material.
<h2>Halogens.</h2>
Explanation:
All of the halogens form salts with alkali metals with the formula MX.
Halogens are the members of group 17 in the periodic table. They have seven electron in their valence shell and tend to form negative ion with minus one charge. They get there name because of their property to form salts. Halogens are very reactive and form salts with the metals.