Calcium fluoride.
Ca is metal, F is non-metal, so they form ionic bond.
Ca as metal can form only positive ion. Ca in the second group, so the charge of Ca ion is 2+. Ca²⁺
F is in the 17th group, so it has 7 electrons on the last level. It is non-metal, non-metal, so it has negative charge -(8-7)=-1. "8" because on the last level cannot be more than 8 electrons. F-ion is F¹⁻.
Ca²⁺ F¹⁻
Number of positive charges should be equal to number of negative charges,
Formula of calcium fluoride
CaF2.
2 atoms Fluorine bond with Calcium.
Complete Question
Questions Diagram is attached below
Answer:
* 
* 
* 
Explanation:
From the question we are told that:
Temperature 
Pressure 
Volume
Generally the equation for gas Constant is mathematically given by



Therefore
Work-done



Generally the equation for internal energy is mathematically given by


Therefore



Answer : The enthalpy of the reaction is, -2552 kJ/mole
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given enthalpy of reaction is,

The intermediate balanced chemical reactions are:
(1)

(2)

(3)

(4)

Now we have to revere the reactions 1 and multiple by 2, revere the reactions 3, 4 and multiple by 2 and multiply the reaction 2 by 2 and then adding all the equations, we get :
(when we are reversing the reaction then the sign of the enthalpy change will be change.)
The expression for enthalpy of the reaction will be,



Therefore, the enthalpy of the reaction is, -2552 kJ/mole
Answer:
length of wire = 38.82 m
Explanation:
∴ 16 gauge ≡ 0.05082 in * ( 2.54 cm/in ) = 0.12908 cm
∴ m spool = 1 Lb = 453.592 g
∴ ρ = 8.92 g/cm³
cross section area:
⇒ A = π*D²/4 = π*(0.12908)²/4 = 0.0131 cm²
⇒ L = ((453.592 g) *(cm³/8.92 g)) / ( 0.0131 cm² )
⇒ L = 3881.765 cm * ( m/100cm) = 38.82 m
Good grief, this stuff got caught in a black hole somewhere. It is terribly dense.
1 mL = 1 cc under normal conditions.
d = mass / volume
m = 20 kg
v = 5 mL
d = 20kg / 5 mL
d = 4 kg / mL
d = 4 kg / cc
A <<<<answer