Mercury boils at 367°C. However, mercury thermometers are made such that they can measure temperature upto 500°C. This is done by:

• maintaining vacuum above the mercury column in the stem of the thermometer

• filling nitrogen gas at high pressure above the mercury column

• filling oxygen gas at high pressure above the mercury column

• filling nitrogen gas at low pressure above the mercury column

An ice-cube of density 900 kg/m³ is floating in the water of density 1000 kg/m³ The percentage of volume of the ice-cube outside the water is:

• 20 %

• 35 %

• 10 %

• 25 %

A tank is filled with water upto height H. When a hole is made at a distance h below the level of water, what will be the horizontal range of water jet?

• 2√h(H - h)

• 4√h(H + h)

• 4√h(H - h)

• 2√h(H + h)

A raft of wood of mass 120 kg floats in water. The weight that can be put on the raft to make it just sink should be (draft = 600 kg/m³) :

• 80 kg

• 50 kg

• 60 kg

• 30 kg

Eight small drops, each of equal charges and radii are coalesce to form a big drop. The capacity of bigger drop in comparison to each smaller drop will be :

• 4 times

• 2 times

• 32 times

• 8 times

The surface tension of the soap solution is T. The work done in forming a soap bubble of radius r, is :

• $8{\mathrm{\pi r}}^2\mathrm{T}$

• $4{\mathrm{\pi r}}^2\mathrm{T}$

• $\frac{4}{3}{\mathrm{\pi r}}^2\mathrm{T}$

• $\frac{8}{3}{\mathrm{\pi r}}^2\mathrm{T}$

177.

Given that the surface tension of water is 75 dyne/cm, its density 1 g/cc and angle of contact zero, the height to which water rises in a capillary tube of 1 mm diameter is (Take g = 10 m/s²)

• 9.0 cm

• 7.5 cm

• 6.0 cm

• 3.0 cm

Compressibility of water is 5 x 10^-10 m² /N. The change in volume of 100 mL water subjected to 15 x 10⁶ Pa pressure will

• no change

• increase by 0.98 mL

• decrease by 0.75 mL

• increase by 1.50 mL

If there were no gravity, which of the following will not be there for a fluid ?

• Viscosity

• Surface tension

• Pressure

• Archimedes' upward thrust

If a liquid does not wet a solid surface, then its angle ofcontact is

• acute angle

• obtuse angle

• right angle

• None of these