Calculate the wave number of photon emitted during transition from the orbit of $$n=3$$ to $$n=2$$ in hydrogen atom $$\left(R_H=109677 \mathrm{~cm}^{-1}\right)$$.

What is the molar concentration of acetic acid if value of it's, dissociation constant is $$1.8 \times 10^{-5}$$ and degree of dissociation is 0.02 ?

An ideal gas absorbs $$210 \mathrm{~J}$$ of heat and undergoes expansion from $$3 \mathrm{~L}$$ to $$6 \mathrm{~L}$$ against a constant external pressure of $$10^5 \mathrm{~Pa}$$. What is the value of $$\Delta U$$ ?

What is the molecular formula of $$p$$-toluidine?