Which of the following is the only taxonomic category that has a real existence?

Two tuning forks $A$ and $B$ produce $8\ Hz$ beats per second when sounded together. $A$ gas column $37.5\ cm$ long in a pipe closed at one end resonates in its fundamental mode with fork $A$,whereas a column of length $38.5\ cm$ of the same gas in a similar pipe is required for a similar resonance with fork $B$. The frequencies of these two tuning forks are:

Which of the following biomolecules acts as specific catalysts in biological reactions?

$A$ ball is projected with velocity $V_0$ at an angle of elevation $30^\circ$. Mark the correct statement.

Which of the following is a geocarpic fruit?

The colour of the bead in the borax bead test is mainly due to the formation of: