Which of the following represents the correct pathway of blood circulation in the human heart?

Rearrange the following ($I$ to $IV$) in the order of increasing masses:
$I$. $0.5$ mole of $O_3$
$II$. $0.5$ g-atoms of oxygen
$III$. $3.011 \times 10^{23}$ molecules of $O_2$
$IV$. $5.6$ $L$ of $CO_2$ at $STP$

$A$ 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:

The major product in the following reaction is:

Which of the following is an example of an interstitial hydride?

$A$ small sphere carrying a charge $q$ is suspended by a string of length $L$ between two parallel plates. The time period of the pendulum is $T_0$. When the capacitor is charged,the time period changes to $T$. The ratio $T/T_0$ is equal to: