Which element from following combines with hydrogen to form compound having lowest acidic strength?

If decomposition of hydrogen peroxide is a first order reaction, it's rate law equation can be represented as

The FCC unit cell of a compound contains ions of $$\mathrm{A}$$ at the corner and ions of $$\mathrm{B}$$ at the centre of each face, what is the formula of the compound?

To obtain 3-methylbutan-2-ol from acetaldehyde, the Grignard's reagent used is