The arrangement of X^$$-$$ ions around A⁺ ion in solid AX is given in the figure (not drawn to scale). If the radius of X^$$-$$ is 250 pm, the radius of A⁺ is

A compound M_pX_q has cubic close packing (ccp) arrangement of X. Its unit cell structure is shown below. The empirical formula of the compound is

Among the electrolytes Na$$_2$$SO$$_4$$, CaCl$$_2$$, Al$$_2$$(SO$$_4$$)$$_3$$ and NH$$_4$$Cl, the most effective coagulating agent for Sb$$_2$$S$$_3$$ sol is

Among the following, the surfactant that will form micelles in aqueous solution at the lowest molar concentration at ambient condition is: