Substance m is a blue, brittle solid. substance n is a colorless, flammable gas. what can we predict about the compound created when m and n form a covalent bond?

As given

Substance M is a blue, brittle solid: It means it is a solid. However we cannot predict the nature of the element. It can be non metal or metal. So it can be highly electropositive or electronegative. It can lose or gain electron or it may share electrons to form covalent bonds

Similarly

Substance N is a colorless, flammable gas: it must be non metal. But we cannot predict the exact composition or nature of the gas.

Flammable colourless means it can be hydrogen.

So we can say that we cannot comment on the nature of the compound formed by combination of M and N.

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.