physics ncert solutions class 11th

Match List - I with List – II.
List - I
(a) 10 km height over earth's surface
(b) 70 km height over earth's surface
(c) 180 km height over earth's surface
(d) 270 km height over earth's surface
List - II
(i) Thermosphere
(ii) Mesosphere
(iii) Stratosphere
(iv) Troposphere

A force F = (î + 2ĵ + 3k)N acts at a point (4î + 3ĵ – k)m. Then the magnitude of torque about the point (î + 2ĵ + k)m will be √xN m. The value of x is

Number of molecules in a volume of 4 cm³ of a perfect monoatomic gas at some temperature T and at a pressure of 2 cm of mercury is close to? (Given, mean kinetic energy of a molecule (at T) is 4 * 10⁻¹⁴erg, g = 980 cm/s², density of mercury = 13.6 g/cm³ )

A wheel is rotating freely with an angular speed ω on a shaft. The moment of inertia of the wheel is I and the moment of inertia of the shaft is negligible. Another wheel of moment of inertia 3I initially at rest is suddenly coupled to the same shaft. The resultant fractional loss in the kinetic energy of the system is:

In a dilute gas at pressure P and temperature T, the mean time between successive collisions of a molecule varies with T as:

For a transverse wave traveling along a straight line, the distance between two peaks (crests) is 5 m, while the distance between one crest and one trough is 1.5 m. The possible wavelengths (in m ) of the waves are:

Dimensional formula for thermal conductivity is (here K$$ denotes the temperature):

The mean free path and the average speed of oxygen molecules at 300 K and 1 atm are 3 * 10⁻⁷ m and 600 m/s, respectively. Find the frequency of its collisions.