The compound,found in nature in gas phase but ionic in solid state is

Which among the following complexes has square pyramidal geometry?

$A$ tuning fork vibrating with a sonometer having $20 \, cm$ wire produces $5$ beats per sec. The beat frequency does not change if the length of the wire is changed to $21 \, cm$. The frequency of the tuning fork must be ..... $Hz$.

An electrolytic cell contains a solution of $Ag_2SO_4$ and has platinum electrodes. $A$ current is passed until $1.6 \ g$ of $O_2$ has been liberated at the anode. The amount of silver deposited at the cathode would be ............. $g$.

Which is the correct option for sulphur-containing amino acids?

The symbiotic association between algae and fungi is known as -