Which of the following is an unsuitable habitat for algae?

In a $\triangle ABC$,if $\frac{\cos A}{a} = \frac{\cos B}{b} = \frac{\cos C}{c}$,then $\triangle ABC$ is

Eight different letters of an alphabet are given. Words of four letters from these are formed. The number of such words with at least one letter repeated is :

Somaclones are obtained through which of the following?

The major product of the following reaction is:

$A$ metallic ring connected to a rod oscillates freely like a pendulum. If now a magnetic field is applied in a horizontal direction so that the pendulum now swings through the field,the pendulum will