Which of the following crops were introduced into India from the New World?

With a standard rectangular bar magnet of length $l$,breadth $b$ $(b \ll l)$,and magnetic moment $M$,the time period of the magnet in a vibration magnetometer is $4 \ s$. If the magnet is cut normal to its length into four equal pieces,the time period (in seconds) with one of the pieces is:

The number of common tangent$(s)$ to the circles $x^2 + y^2 + 2x + 8y - 23 = 0$ and $x^2 + y^2 - 4x - 10y + 19 = 0$ is:

Where does the process of cleavage begin in humans?

Which of the following elements is a constituent of biotin?

The $pH$ of $0.05 \ M$ acetic acid is $(K_a = 2 \times 10^{-5})$