The factor that is generally responsible for higher melting point is intermolecular forces. The compounds that are covalent in nature are made of molecules rather than ions. It has been seen that some of the covalent compounds have polar molecules at one end, due to which the one end has more electronegative force than the other. The electrostatic force that is bounding the compound is the main cause of higher melting point of this compound. So it is true that with the increase of polarity of a compound creates higher melting point. .. hope I helped
The third one down: "When barium hydroxide is mixed with ammonium chloride, ice crystals form on the outside of the container."
This is because an endothermic reaction [process] takes in more energy than it releases. Therefore because a decrease in energy leads to a decrease in temperature, the ice crystals forming show that it must be a endothermic reaction [process].
Hope this helps! :)
AJ
Ionic compounds are formed between oppositely charged ions.
A binary ionic compound is composed of ions of two different elements - one of which is a positive ion(metal), and the other is negative ion (nonmetal).
To write the empirical formula of binary ionic compound we must remember that one ion should be positive and other ion should be negative, then only the correct formula should be written. To write the empirical formula the charges of opposite ions should be criss-crossed.
First empirical formula of binary ionic compound is written between
First Formula would be 
Second empirical formula is between 
Second Formula would be 
Note : When the subscript are same they get cancel out, so
would be written as 
Third empirical formula is between 
Third Formula would be :
Forth empirical formula is between 
Forth Formula would be :
or 
Note- The subscript will be simplified and the formula will be written as
.
The empirical formula of four binary ionic compounds are : 
Answer:
Formula of the compound = 
Explanation:
Given,
No. of mole of O = 8.20 mol
No. of mole of P = 3.30 mol
Chemical formula = 
Ratio of P and O = 

formula of the compound = 
Answer:
462g
Explanation:
First, let us calculate the molar mass of Cu(CN)2. This is illustrated below:
Molar Mass of Cu(CN)2 = 63.5 + 2(12+14) = 63.5 + 2(26) = 63.5 + 52 = 115.5g/mol
Number of mole of Cu(CN)2 given from the question = 4moles
Mass = number of mole x molar Mass
Mass of Cu(CN)2 = 4 x 115.5
Mass of Cu(CN)2 = 462g