Answer:

Explanation:
Here, we want to convert J to cal
Mathematically:

Thus, to get our answer in cal, we divide the value given by 4.186
We have that as:
If 0.5 L of solution contains 4 mol
then let 1 L of solution contain x mol
⇒ (0.5 L) x = (4 mol) (1 L)
x = (4 mol · L) ÷ (0.5 L)
x = 8 mol
Thus the molarity of the Sodium Chloride solution is 8 mol / L OR 8 mol/dm³.
The change is called melting
<h3>Further explanation</h3>
Basic oxides ⇒ metal(usually alkali/alkaline earth) +O₂
L + O₂ ⇒ L₂O
L + O₂ ⇒ LO
Dissolve in water becomes = basic solution
L₂O+H₂O⇒ 2LOH
LO + H₂O⇒ L(OH)₂
So the basic oxides : Na₂O and MgO
Na₂O + H₂O⇒NaOH
MgO +H₂O⇒Mg(OH)₂
The aqueous solution of CO₂(dissolve in water)
CO₂ + +H₂O⇒ H₂CO₃(carbonic acid)