Helium mixed with oxygen is used in the treatment of

Which among the following complexes has square pyramidal geometry?

Magnetic induction at the centre of a circular loop of area $\pi \ m^2$ is $0.1 \ T$. The magnetic moment of the loop is ( $\mu_0 = \text{permeability of air}$ ).

The colour of light absorbed by an aqueous solution of $CuSO_4$ is

Which of the following oxoacids of phosphorus has the lowest oxidation state of phosphorus?

Three masses $700\,g, 500\,g$ and $400\,g$ are suspended at the end of a spring as shown and are in equilibrium. When the $700\,g$ mass is removed,the system oscillates with a period of $3\,s$. When the $500\,g$ mass is also removed,it will oscillate with a period of .... $s$.