Methanogens belong to:

Two circular loops $P$ and $Q$ of radii $r$ and $nr$ respectively are made from a uniform wire. The moment of inertia of $Q$ about its axis is four times that of $P$ about its axis. The value of $n$ is

For $k=1, 2, 3$,the box $B_k$ contains $k$ red balls and $(k+1)$ white balls. Let $P(B_1) = \frac{1}{2}$,$P(B_2) = \frac{1}{3}$,and $P(B_3) = \frac{1}{6}$. $A$ box is selected at random and a ball is drawn from it. If a red ball is drawn,then the probability that it has come from box $B_2$ is:

The materials having negative magnetic susceptibility are

The hybrids are generally found to be superior to their parents; this is because of:

For a plane electromagnetic wave propagating in the $x$-direction,which one of the following combinations gives the correct possible directions for the electric field $(\vec{E})$ and magnetic field $(\vec{B})$ respectively?