Small doubt

CH₃ ke hypeconjugation ke wajah se the N atom will be more basic, enough to react in an acid base reaction with NaHCO₃.
NaNO₂/HCl will not work as there are no hydrogens present on N to facilitate diazotization. Will check about the beta-napthol waala and let you know.

Pritish..the basicity of N will be reduced due to crowding by the two methyl groups and the phenyl group.
So the lone pair of N will not have enough place to leave the atom.

Therefore it may not react with NaHCO₃.

and the compound will give positive test with NaNO₂ /HCl. I've shown the product..

aieee....Activeness of lone pair is reduced due to stearic hindrance. That is why (CH₃)₃N is less basic than (CH₃)₂NH.

+I effect of alkyl groups raises the energy of the lone pair of electrons, thus elevating the basicity. Thus the basicity of an amine may be expected to increase with the number of alkyl groups on the amine. However, there is no strict trend in this regard, as basicity is also governed by other factors mentioned above. Consider the Kb values of the methyl amines given above. The increase in Kb from methylamine to dimethylamine may be attributed to +I effect; however, there is a decrease from dimethylamine to trimethyl amine due to the predominance of steric hindrance offered by the three methyl groups to the approaching Lewis acid.
Source - Wiki
Yes, prongs is right in that specific case.
And about NaNO₂, I forgot about nitrosamine EAS..lol.

Thanks everyone the ans is

YES for NaHCO₃

NO for NaNO2 / H c l , β -napthol / OH-

oooo..so I was right?

Maybe because the electrophilic aromatic substitution with nitrosamine does not give indication of a product like a ppt or a colour?

maybe....organic can be soo confusing sometimes....