Explain why bullets of a gun are cylindrical in shape.

$A$ drop of water detaches itself from the exit of a tap when $(\sigma=$ surface tension of water, $\rho=$ density of water, $R=$ radius of the tap exit, $r=$ radius of the drop $)$

Consider the following statements:
$A.$ Surface tension arises due to extra energy of the molecules at the surface as compared to the molecules in the interior of a liquid.
$B.$ As the temperature of a liquid rises, the coefficient of viscosity increases.
$C.$ As the temperature of a gas increases, the coefficient of viscosity increases.
$D.$ The onset of turbulence is determined by Reynolds number.
$E.$ In a steady flow, two streamlines never intersect.
Choose the correct answer from the options given below:

An air bubble rises from the bottom of a water tank of height $5 \ m$. If the initial volume of the bubble is $3 \ mm^3$, what will be its volume as it reaches the surface (in $mm^3$)? Assume that its temperature does not change. $[g=9.8 \ m \ s^{-2}, 1 \ atm=10^5 \ Pa, \text{density of water}=1 \ g/cm^3]$

An open cubical tank was initially fully filled with water. When the tank was accelerated on a horizontal plane along one of its sides,it was found that one-third of the volume of water spilled out. The acceleration was:

The vertical limbs of a $U$ shaped tube are filled with a liquid of density $\rho$ up to a height $h$ on each side. The horizontal portion of the $U$ tube having length $2h$ contains a liquid of density $2\rho$. The $U$ tube is moved horizontally with an acceleration $g/2$ parallel to the horizontal arm. The difference in heights in liquid levels in the two vertical limbs,at steady state,will be: