JEE Main Mock 99 for JEE & BITSAT Exams

Question 1

A cubical room is formed with 6 plane mirrors. An insect moves along the diagonal of the floor with uniform speed. The velocity of its image relative to the mirror in two adjacent walls (seen by insect) is 20cms^–1. Then the velocity of the image formed in the roof is -

Question 2

The face AC of a prism ABC of refracting angle 30 ° is silvered. A ray is incident on face AB at an angle of 45 ° as shown in figure. The refracted ray undergoes reflection at face AC and retraces its path. The refractive index of the prism is-

Question 3

A mixture of light, consisting of wavelength 590 nm and an unknown wavelength, illuminates Young's double slit and gives rise to two overlapping interference patterns on the screen. The central maximum of both lights coincide. Further, it is observed that the third bright fringe of known light coincides with the 4^th bright fringe of the unknown light. From this data, the wavelength of the unknown light is:

Question 4

Two rods of lengths l₁ and l₂ are made of materials whose coefficient of linear expansions are α₁ and α₂. If the difference between two lengths is independent of temperature-

Question 5

In an isothermal and reversible expansion of 96 g of oxygen at 27 ºC temperature, the work done is 900 R log₁₀2. The ratio of final to initial volume is–

Question 6

A carnot engine, having an efficiency of

as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is

Question 7

Temperature of a diatomic gas is 300 K. If moment of inertia of its molecules is 8.28 × 10^–38 gm-cm², root mean square angular velocity is –

Question 8

The set of values of x satisfying the equation

+ 1 = 0 is-

Question 9

The value of the expression cos

cos

– sin

sin

is

Question 10

Mixture of two salts are not soluble in water but soluble in dilute HCl solution. Mixture can be–

Question 11

A pale green crystalline inorganic salt A. dissolves freely in water. It gives a brown precipitate on addition of aqueous NaOH. The solution of A. also gives a black precipitate on bubbling H₂S in alkaline medium. An aqueous solution of the A. decolorizes the pink colour of the permanganate solution. The metal in the salt solution is–

Question 12

Cast iron is produced in–