Can two streamlines cross each other? Why?

Explain the concept of a tube of flow.

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 $v_p = 20\, m/sec$)

An incompressible liquid flows through a horizontal tube as shown in the following figure. Then the velocity $v$ of the fluid is ....... $m/s$.

$A$ shower head has $25$ circular openings, each with radius $1 \,mm$. The shower head is connected to a pipe with radius $2 \,cm$. If the speed of the water in the pipe is $25 \,cm/s$, what is its speed as it exits the shower head openings (in $\,m/s$)?

The surface of water in a water tank of cross-sectional area $750 \,cm^2$ on the top of a house is '$h$' $m$ above the tap level. The speed of water coming out through the tap of cross-sectional area $500 \,mm^2$ is $30 \,cm/s$. At that instant, $\frac{dh}{dt}$ is $x \times 10^{-3} \,m/s$. The value of '$x$' will be: