Which of the following is a cyclic phosphate?

If $\theta$ lies in the first quadrant and $5 \tan \theta = 4$,then $\frac{5 \sin \theta - 3 \cos \theta}{\sin \theta + 2 \cos \theta}$ is equal to

Which of the following orders are correct?
$I$. Thermal stability : $BeSO_4 < MgSO_4 < CaSO_4 < SrSO_4 < BaSO_4$
$II$. Basic nature : $ZnO > BeO > MgO > CaO$
$III$. Solubility in water : $LiOH > NaOH > KOH > RbOH > CsOH$
$IV$. Melting point : $NaCl > KCl > RbCl > CsCl > LiCl$

Alkali metals lose electrons from which orbitals?

The product of the distinct $(2n)^{\text{th}}$ roots of $1+i\sqrt{3}$ is equal to:

The incentre of the triangle with vertices $(1, \sqrt{3})$,$(0, 0)$ and $(2, 0)$ is