Question

1-) Of the compounds shown below, which is ionic? A) KC6H6O B) C4H9NH2 C) H2CO3 D) SO3 E) HF

2-) Choose the set below that only has covalently bonded compounds. A) NH4Br, N2H4, HBr

B) I2, H2S, NaI

C) Al, O3, As4

D) C6H6, H2, CsCl

A) BCl3, SiF4, NCl3

3-) Sodium chloride has a crystal structure where the chlorines are situated at each corner and each face. How many zinc ions are in the unit cell?

A) 1 B) 6 C) 3 D) 2 E) 4

4-) A compound is insoluble in water but dissolves in oil. The bonding in the compound is likely______.

A) an ionic solid B) a molecular solid C) a metallic solid D) a network covalent solid E) an elemental solid.

5-) If highly purified silicon is doped with As, what type of semiconductor do you obtain? A) fermi-level type B) n-type C) p-type D) q-type E) s-type

Answer 1

The simple diffrence between ionic and covalent compounds is that Ionic compounds made by Metal-non metal combination whereas Covalent compound is made by Non metal-non metal combination.

If electronegativity difference is more than 1.9 between two atoms,the bond is ionic.

If electronegativity difference is in the range of 0.5 to 1.9 between two atoms,the bond is polar covalent.

When electronegativity difference is less than 0.5 then the bond is non polar covalent.

1) KC₆H₆O is ionic

C₄H₉NH₂ - Covalent

H₂CO₃-Covalent

SO₃-Covalent

HF - polar covalent.

2) BCl₃,SiF₄ and NCl₃ are covalent

3) NaCl unit cell has face centered cubic structure with anions and cation with the coordination number 6.

answer:B.

4) A network of covalent solid dissolves in oil but not water because water is apolar solvent whereas covalent solid is non polar.

5) When V-group element is a doping agent,then it produce n-type semiconductor where As is a V-group element acting as doping agent.

Answer is B.

If III-group element acts as doping agent,it produce p-type semiconductor.