Which from following compounds contains complex cations and anions?

If concentration of reactant ' $A$ ' is increased by 10 times, rate of reaction increases 100 times. What is order of reaction if rate law is $r=k[A]^r$ ?

Which from following lanthanoids exhibits +4 oxidation state in $\mathrm{F}^7$ configuration?

Which among the following salts turns red litmus blue in its aqueous solution?