Which metal does not react with cold water but releases $H_2$ gas upon reacting with steam?

When a bucket is half full,the weight of the bucket and the water is $10 \ kg$. When the bucket is two-thirds full,the total weight is $11 \ kg$. What is the total weight (in $kg$),when the bucket is completely full?

In a $dc$ motor,induced $e.m.f.$ will be maximum

Which of the following biomolecules acts as specific catalysts in biological reactions?

The r.m.s. velocity of $CO_2$ at a temperature $T$ (in kelvin) is $x \ cm \ s^{-1}$. At what temperature (in kelvin),the r.m.s. velocity of nitrous oxide would be $4 x \ cm \ s^{-1}$ (in $T$)? (Atomic weights of $C, N$ and $O$ are respectively $12, 14$ and $16$)

The moment of inertia of a uniform circular disc is maximum about an axis perpendicular to the disc and passing through which of the following points?