COMEDK Mock Test - 3 - JEE MCQ

Half-life of a radioactive substance A is 4 days. The probability of a nucleus that, from the given sample that it will decay in two half-lives is

Two bulbs consume the same power when operated at 200 V and 300 V respectively. When these bulbs are connected in series across a DC source of 400 V, then the ratio of power consumed across them is

A polariser - analyser set is adjusted such that the intensity of light coming out of the analyser is just 10% of the original intensity. Assuming that the polariser - analyser set does not absorb any light, the angle by which the analyser needs to be rotated further to reduce the output intensity to be zero, is

For a series LCR circuit with R = 100 Ω, L = 0.5 mH, C = 0.1 pF connected across 220 V-50 Hz AC supply, the phase angle between current and supplied voltage and the nature of the circuit is

In the circuit shown in figure, A and B are two cells of the same emf, E and of internal resistances r_A and r_B, respectively. L is an ideal inductor and C is an ideal capacitor. The key K is closed. When the current in the circuit becomes steady, what should be the value of R so that the potential difference across the terminals of cell A is zero?

A body is projected up a smooth inclined plane with velocity v from the point A as shown in the figure. The angle of inclination is 45° and the top is connected to a well of diameter 40 m. If the body just manages to cross the well, what is the value of v? Length of the inclined plane is 20√2 m.

A fly wheel is accelerated uniformly from rest and rotates through 5 rad in the first second. The angle rotated by the fly wheel in the next second will be:

In an adiabatic process internal energy of gas

A charge Q is moving distance in the magnetic field  Find the value of work done by 

The quantity of electricity required to liberate 112 cm³ of hydrogen at STP from acidified water is

When ether is exposed in air for sometime, an explosive substance produced is

Use of hot air balloons in sports and metereological observations is an application of

Zn²⁺aq) + 2e^- → Zn(s). This is

Irrespective of the source, pure sample of water always yields 88.89% mass of oxygen and 11.11% mass of hydrogen. This is explained by the law of

If the pressure on a NaCl structure is increased, then its co-ordination number will

The structure shown below is of which well-known drug molecule?

The metal ion (in gaseous state) with lowest spin-only magnetic moment value is

At 25°C and 1 atm pressure, the enthalpy of combustion of benzene (I) and acetylene (g) is -3268 kJ mol^-1 and -1300 kJ mol^-1, respectively. The change in enthalpy for the reaction 3C₂H₂(g) → C₆H₆(l) is

The mode of the following items is 0, 1, 6, 7, 2, 3, 7, 6, 6, 2, 6, 0, 5, 6, 0

Two common tangents to the circle x² + y² = 2a² and parabola y² = 8ax are

If  are unit vectors and then the value of is equal to

If P(S) = 0.3, P(T) = 0.4, S and T are independent events, then P(S/T)=

The eccentricity of the hyperbola in the standard form  passing through (3, 0) and (3√2, 2) is

What is the solution of the differential equation 2x³y dy + (1 - y²)(x²y² + y² - 1) dx = 0?

A unit vector in xy-plane, which makes an angle of 45° with the vector  and an angle of 60° with the vector , is

On the ellipse 4x² + 9y² = 1, the point at which the tangents are parallel to the line 8x = 9y is

Area bounded by parabola y² = x and st.line 2 y = x is