Which of the following oxides will not react with $NaOH$?

The basis of the quantum mechanical model of an atom is

At $80\,^oC$,the vapour pressure of pure liquid $A$ is $520\,mmHg$ and that of pure liquid $B$ is $1000\,mmHg$. If a mixture of $A$ and $B$ boils at $80\,^oC$ and $1\,atm$ pressure,the amount of $A$ in the mixture is $........$ $mol\,\%$.

In Earthworm,the dorsal wall of the intestine from the $26^{th}$ segment to the $95^{th}$ segment forms a median internal fold called:

The number of ways that $8$ beads of different colours can be strung as a necklace is

Which of the following is a favourable factor for cation formation?