Ephemerals are xerophytes that are:

An organ pipe $P_1$ closed at one end is vibrating in its first overtone. Another pipe $P_2$ open at both ends is vibrating in its third overtone. They are in resonance with a given tuning fork. The ratio of the length of $P_1$ to that of $P_2$ is

Which one of the following is most acidic?

Which has the maximum number of molecules among the following?

If $\bar{a}$ and $\bar{b}$ are two unit vectors such that $\bar{a}+2 \bar{b}$ and $5 \bar{a}-4 \bar{b}$ are perpendicular to each other,then the angle between $\bar{a}$ and $\bar{b}$ is

In the given branch $AB$ of a circuit, a current $I = (10t + 5) \, A$ is flowing, where $t$ is time in seconds. At $t = 0$, the potential difference between points $A$ and $B$ $(V_A - V_B)$ is......$V$.