Explanation:
Igneous rocks are formed by the crystallisation of a magma. The difference between granites and basalts is in silica content and their rates of cooling. A basalt is about 53% SiO2, whereas granite is 73%. Intrusive, slowly cooled inside the crust.
The formula of a compound is 
Given:
The ions
and 
To find:
The formula for ions
and 
Solution:
The ion with a positive charge (cation) = nickel ion = 
The ion with a negative charge (anion) = nitrate ion = 
Valency on nickel ion = 2
Valency on nitrate ion = 1
Using the criss-cross method as shown in image
The formula of a compound : 
The name of a compound is nickel(II) nitrate

The formula of a compound is 
Learn more about ions here:
brainly.com/question/24389121?referrer=searchResults
the summer solstice should be your answer
Polymerization
For example:
nCH₂=CH₂ ---p,T,kat.----> -[-CH₂-CH₂-]- n