Class 11th

An ideal gas in a closed container is slowly heated. As its temperature increases, which of the following statements are true?
(a) the mean free path of the molecules decreases
(b) the mean collision time between the molecules decreases.
(c) the mean free path remains unchanged.
(d) the mean collision time remains unchanged.

A particle is moving 5 times as fast as an electron. The ratio of the de-Broglie wavelength of the particle to that of the electron is 1.878 * 10⁻⁴. The mass of the particle is close to:

A satellite is moving in a low nearly circular orbit around the earth. Its radius is roughly equal to that of the earth's radius Rₑ. By firing rockets attached to it, its speed is instantaneously increased in the direction of its motion so that it become √(3/2) times larger. Due to this the farthest distance from the centre of the earth that the satellite reaches is R. Value of R is:

Pressure inside two soap bubbles are 1.01 and 1.02 atmosphere, respectively. The ratio of their volumes is

A block of mass m = 1 kg slides with velocity v = 6 m/s on a frictionless horizontal surface and collides with a uniform vertical rod and sticks to it as shown. The rod is pivoted about O and swings as a result of the collision making angle θ before momentarily coming to rest. If the rod has mass M = 2 kg, and length l = 1 m, the value of θ is approximately: (take g = 10 m/s²)

Which of the following is tautology?

The imaginary part of (3 + 2√-54)¹/² - (3 - 2√-54)¹/² can be

Let n > 2 be an integer. Suppose that there are n Metro stations in a city located along a circular path. Each pair of stations is connected by a straight track only. Further, each pair of nearest stations is connected by blue line, whereas all remaining pairs of stations are connected by red line. If the number of red lines is 99 times the number of blue lines, then the value of n is

The work function of sodium metal is 4.41 * 10⁻¹⁹ J. If photons of wavelength 300 nm are incident on the metal, the kinetics energy of the ejected electrons will be (h = 6.63 * 10⁻³⁴ Js; c = 3 * 10⁸ m/s) * 10⁻²¹ J. [numerical value].

The heat of combustion of ethanol into carbon dioxides and water is –327kcal at constant pressure. The heat evolved (in cal) at constant volume at 27°C (if all gases behave ideally) is (R=2calmol⁻¹K⁻¹) [numerical value].