$A$ uniform meter scale is supported at its $20 \ cm$ mark. $A$ body suspended from the $10 \ cm$ mark keeps the scale horizontal. However,the scale becomes unbalanced if the body is completely immersed in water. To regain the balance,the body is shifted to the $8 \ cm$ mark. Therefore,the specific gravity of the material of the body is

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:

What is dynamic lift?

$A$ 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 $)$

The volume of an air bubble becomes three times as it rises from the bottom of a lake to its surface. Assuming atmospheric pressure to be $75 \ cm$ of $Hg$ and the density of water to be $1/10$ of the density of mercury,the depth of the lake is ....... $m$.

Fill in the blanks using the word$(s)$ from the list appended with each statement:
$(a)$ Surface tension of liquids generally . . . with temperatures (increases / decreases)
$(b)$ Viscosity of gases . . . with temperature,whereas viscosity of liquids . . . with temperature (increases / decreases)
$(c)$ For solids with elastic modulus of rigidity,the shearing force is proportional to . . .,while for fluids it is proportional to . . . (shear strain / rate of shear strain)
$(d)$ For a fluid in a steady flow,the increase in flow speed at a constriction follows (conservation of mass / Bernoulli's principle)
$(e)$ For the model of a plane in a wind tunnel,turbulence occurs at a . . . speed for turbulence for an actual plane (greater / smaller)