List of practice Questions

An unbiased coin is tossed n times. The probability that head will present itself, odd number of times is
An organic compound (A), $C_2H_5NO_2$ gives on reduction another compound (B) $C_2H_7N$. The reaction of nitrous acid on (B) evolves nitrogen and gives another compound (C) $C_2H_6O$. The compound (C) on oxidation gives acetic acid. The compounds A, B, C are
An organic compound with the formula $C_6H_{12}O_6$ forms a yellow crystalline solid with phenylhydrazine and gives a mixture of sorbitol and mannitol when reduced with sodium. Which among the following could be the compound ?
An open vessel containing air is heated from 27$^\circ$C to 127$^\circ$C. The fraction of air originally present which goes out of it is
An ore after levigation is found to have basic impurities. Which of the following can be used as flux during smelting ?
An open tank with a square base and vertical sides is to be constructed from a metal sheet so as to hold a given quantity of water. The cost of the material will be least when depth of the tank is
An open flask contains air at $27^?C$, calculate the temperature to which it should be heated such that one third of air measured at final temperature escapes out.
An oil-soluble dye is mixed with an emulsion and emulsion remains colourless. Then, it is
An open box with a square base is to be made out of a given quantity of a cardboard of area $c^2$ square units. The maximum volume of the box is (in cubic units)
An object is moving towards a concave mirror of length 24 cm. When it is at a distance of 60 cm from the mirror its speed is 9cm/s, the speed of its image at that instantis
An object is projected in x-y plane from the origin at t=0 and its velocity changes according to relation $\bar{v} = a\hat{i}+bx\hat{j}$. Equation of path of particle is
An object of mass $40\, kg$ and having velocity $ 4\, m s^{-1}$ collides with another object of mass $60\, kg$ having velocity $ 2 \,ms^{-1}$. The loss of energy when the collision is perfectly inelastic
An LCR series circuit containing a resistance of $120\Omega$ has angular resonance frequency $4\times 10^5$ rad $S^{-1}$. At resonance the voltage across resistance and inductance are 60V and 40V respectively. Then the values of L agd C are respectively
An $n-p-n$ transistor in a common-emitter mode is used as a simple voltage-amplifier with a collector- current of $4 \,mA$. The terminals of a $8\, V$ battery is connected to the collector through a load-resistance $R_L$ and to the base through a resistance $R_B$. The collector-emitter voltage $V_{CE} = 4 \,V$, the base-emitter voltage $V_{BE} = 0.6 \,V$ and the current amplification factor $\beta_{dc} = 100$. Then
An n-type semiconductor is formed
An object is gently placed on a long conveyer belt moving with a speed of $5 \,m \,s^{-1}$. If the coefficient of friction between the block and the belt is $0.5$ the block will slide on the belt up to a distance (Take $g = 10\, m\, s^{-2}$)
An ionic solid is a poor conductor of electricity because
An iron block of sides $50\, cm$ $\times 8 \,cm$ $\times15 \,cm$ has to be pushed along the floor. The force required will be minimum when the surface in contact with ground is
An $LC$ circuit contains a $20\,mH$ inductor and a $50\, \mu F$ capacitor with an initial charge of $10\, mC$. The resistance of the circuit is negligible. Let the instant at which the circuit which is closed be $t = 0$. At what time the energy stored is completely magnetic?
An inductor of inductance L and resistor of resistance R are joined in series and connected by a source of frequency $\omega$. Power dissipated in the circuit is
An infinitely long rod lies along the axis of a concave mirror of focal length . The near end of the rod is a fa distance $u > f$ from the mirror. Its image will have a length
An insect trapped in a circular groove of radius $12\,cm$ moves along the groove steadily and completes $7$ revolutions in $100\,s$. The linear speed of the insect is
An important criterion for modern day classification is
An inductor of $30\,mH$ is connected to a $220\,V$, $100\,Hz$ ac source. The inductive reactance is
An inductor of inductance L = 400 mH and resistors of resistance $R_1=4\Omega$ and $R_1=4\Omega$ are connected to battery of emf 12V as shown in the figure. The internal resistance of the battery is negligible. The swich S is closed at t = 0. The potential drop across L , as a function of time is