The restriction of emission line spectrum for H-atom/H-like species is given by selection rule. For H-like species the transitions which do not follow the restrictions given below are forbidden. 

$\text{ Rule: }\mathrm{\Delta n}=\text{ any value; }\mathrm{\Delta l}=\pm 1;\mathrm{\Delta m}=0,\pm 1$

According to this rule following transitions are not allowed:

While solving questions related to it, you should know about the series of lines in the hydrogen spectrum i.e, Lyman series, Balmer series, Paschen series, Brackett series, Pfund series. Apart from this, you should be aware of the expression that describes the series of lines:

ν=109677$\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)$cm⁻¹

where n_1​=1,2....

n_2​=n_1​+1, n₁​+2...