Which of the following is an oxoacid?

Match the following:

List-$I$	List-$II$
$(A)$ Electron deficient hydride	$(I)$ $CH_4$
$(B)$ Electron precise hydride	$(II)$ $B_2H_6$
$(C)$ Electron rich hydride	$(III)$ $CaH_2$
$(D)$ Saline hydride	$(IV)$ $NiH_{0.6}$
	$(V)$ $PH_3$

$A$ candidate takes three tests in succession and the probability of passing the first test is $p$. The probability of passing each succeeding test is $p$ if he passes the preceding one,or $\frac{p}{2}$ if he fails the preceding one. The candidate is selected if he passes at least two tests. The probability that the candidate is selected is:

Which of the following prevents the collapsing of the trachea?

Which of the following pairs of elements cannot form an alloy?

For the reaction $A + 2B \rightleftharpoons 2C + D$,the initial concentration of $A$ is $a$ and the initial concentration of $B$ is $1.5$ times that of $A$. If the concentrations of $A$ and $D$ are equal at equilibrium,what will be the concentration of $B$ at equilibrium?