Classify the solid state of the following substances as ionic crystals, covalent crystals, molecular crystals, or metallic crystals:
(a) co2
(b) b12
(c) s8
(d) kbr
(e) mg
(f) sio2
(g) licl
(h) cr

Explanation:

There are four type of crystals possible in solids state , given as follows -

1. Ionic crystals -

In this type of crystals ionic bond is involved for the bonding between two atoms , which connects two oppositely charged atoms , i.e. , cation and anion together .

The ionic crystal from the given options are -

(d) KBr and (g) LiCl .

2. Covalent crystals -

The bond formed in these type of crystals are from share the electrons , i.e. making a covalent bond .

Hence ,

From the given options , the covalent crystals are -

(b) B₁₂  and  (f) SiO₂ .

3. Molecular crystals -

weak intermolecular forces , like the dispersion forces , holds the atoms together , generating a molecular crystal .

Hence ,

From the given options , the molecular crystals are -

(a) CO₂ and (c) S₈

4. Metallic crystal -

The type of bond , which make up a metallic crystal is , the metal cation with the delocalized electrons .

Hence ,

From the given options , the metallic crystals are -

(e) Mg and (h) Cr

the formula would be mgso4

mgso[subscript]4

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.