Which of the following metallic hydroxides does not dissolve in a sodium hydroxide solution?

The equation of trajectory of a projectile is $y=10 x-\left(\frac{5}{9}\right) x^2$. If we assume $g=10 \ m/s^2$,the range of the projectile (in metres) is:

The locus of the point $z=x+iy$ satisfying $\left|\frac{z-2i}{z+2i}\right|=1$ is

The half-life of a radioactive element is $10 \ h$. The fraction of initial radioactivity of the element that will remain after $40 \ h$ is

The vapor pressure of water at $80\,^oC$ is $355.5\, mm$ of $Hg$. $A$ $100\, mL$ vessel contains $O_2$ gas at $80\,^oC$ saturated with water vapor,and the total pressure is $760\, mm$ of $Hg$. If the contents of the vessel are transferred to a $50\, mL$ vessel at the same temperature,what will be the partial pressure of $O_2$ in $mm$?

Assign $A, B, C, D$ from the given type of reaction.
$NaCl + AgNO_3 \longrightarrow AgCl \downarrow + NaNO_3$