Can two streamlines cross each other? Why?

The cylindrical tube of a spray pump has a cross-section of $8.0 \; cm^{2}$,one end of which has $40$ fine holes each of diameter $1.0 \; mm$. If the liquid flow speed inside the tube is $1.5 \; m \, min^{-1}$,what is the speed (in $m/s$) of ejection of the liquid through the holes?

Water is flowing through a tube of non-uniform cross-section. The ratio of the radius at the entry and exit end of the pipe is $3:2$. Then the ratio of velocities at the entry and exit of the liquid is:

$A$ motor of power $P_0$ is used to deliver water at a certain rate through a given horizontal pipe. To increase the rate of flow of water through the same pipe $n$ times,the power of the motor is increased to $P_1$. The ratio of $P_1$ to $P_0$ is

In the given figure,the velocity of the fluid $v = $ . . . . . . $m/s$.

In the figure shown,a liquid is flowing through a tube at the rate of $0.1\, m^3/sec$. The tube is branched into two semicircular tubes of cross-sectional area $A/3$ and $2A/3$. The velocity of liquid at $Q$ is ......... $m/sec$. (The cross-section of the main tube $= A = 10^{-2}\, m^2$ and $v_p = 20\, m/sec$)