Gravitation — JEE physics STD 12 Science — Question

Assertion : The angle of contact of a liquid decrease with increase in temperature.
Reason : With increase in temperature, the surface tension of liquid increase.

Assertion : The stars twinkle while the planets do not.
Reason : The stars are much bigger in size than the planets.

Assertion : A capacitor of suitable capacitance can be used in an ac circuit in place of the choke coil.
Reason : A capacitor blocks dc and allows ac only.

Assertion : A potentiometer of longer length is used for accurate measurement.
Reason : The potential gradient for a potentiometer of longer length with a given source of e.m.f. becomes small.

Assertion : On a rainy day sound travel slower than on a dry day.
Reason : When moisture is present in air the density of air increases.

Assertion : Mountain roads rarely go straight up the slope.
Reason : Slope of mountains are large therefore more chances of vehicle to slip from roads.

Assertion : To empty an oil tank, two holes are made.
Reason : Oil will come out two holes so it will emptied faster.

Assertion : When temperature of cold junction of a thermocouple is lowered, the value of neutral temperature of this thermocouple is raised.
Reason : When the difference of temperature of two junction is raised, more thermo e.m.f. is produced.

Assertion : lt is hotter over the top of a fire than at the same distance on the sides.
Reason : Air surrounding the fire conducts more heat upwards.

Assertion : The internal energy of an isothermal process does not change.
Reason : The internal energy of a system depends only on pressure of the system.