Which actinoid from following in its +3 state has largest size?

Which of the following halogens does always show oxidation state -1 ?

Which from following carbohydrates produces glucose, galactose and fructose on hydrolysis?

What is degree of dissociation of $\mathrm{CH}_3 \mathrm{COOH}$ if, $\wedge^{\circ}\left(\mathrm{CH}_3 \mathrm{COO}^{-}\right)=50 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$, $\wedge^{\circ}\left(\mathrm{H}^{+}\right)=350 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ and molar conductivity of $5 \times 10^{-2} \mathrm{M} \mathrm{CH}_3 \mathrm{COOH}$ is $20 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ ?