For the preparation of sodium thiosulphate by the "Springs reaction",the reactants used are

How is the presence of $SO_{2}$ detected?

The electronic configuration of chalcogens in their outermost orbit is:

The incorrect statement$(s)$ about $O_3$ is (are):

$A$ pale yellow solid molecule $(A)$ having crown shape is heated with conc. $H_2SO_4$. It gives a suffocating smell of gas $(B)$,which when passed through starch iodate paper,turns it blue. The gas $(B)$ is:

Identify the element having general electronic configuration $ns^2 np^4$ from the following.