Question

1. choose the best answer.

the property of ionic compounds that allows them to have high melting points is ____.
their crystalline structure
the low amount of energy required to break their bonds
their brittle structure
the strength of their bonding

1. choose the best answer.

which of the following is not a polyatomic ion?
nh₄¹+
cn¹-
ca²+
no₃¹-

Explanation:

• For question 4: Ionic compounds have strong electrostatic forces (ionic bonds) between ions. High melting points result from the need to overcome these strong bonds. A crystalline structure (while a property of ionic compounds) doesn't directly explain high melting points. Brittle structure is a different property. Low energy to break bonds would mean low melting points (opposite of what's needed).
• For question 5: A polyatomic ion is an ion composed of more than one atom. \(NH_4^{1 +}\) (ammonium, made of N and H), \(CN^{1 -}\) (cyanide, made of C and N), and \(NO_3^{1 -}\) (nitrate, made of N and O) are polyatomic. \(Ca^{2+}\) is a single - atom ion (calcium ion).

Answer:

1. the strength of their bonding
2. \(Ca^{2+}\)