List of practice Questions

A $12.5\, eV$ electron beam is used to bombard gaseous hydrogen at room temperature. It will emit :

The number of real circles cutting orthogonally the circle $x^2 + y^2 + 2x - 2y + 7 = 0$ is

The ore chromite is

A sphere of radius R has a volume density of charge $? = kr$, where r is the distance from the centre of the sphere and k is constant. The magnitude of the electric field which exists at the sur ace o the sphere is given by ($e_0$ = permittivity of the free space)

For photoelectric emission from certain metal the cutoff frequency is v. If radiation of frequency 2v impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass) :

The correct formula of plaster of Paris is

Pigment containing membranous extensions in some cyanobacteria are

In the given figure container A holds an ideal gas at a pressure of $ 50\times 10^{5}\, Pa$ and a temperature of $300 \,K$. It is connected by a thin tube (and a closed) container $B$, with four times the volume of $A$. Container $B$ holds same at a pressure of $ 1.0\times 10^{5} \, Pa$ and a temperature of $400 \,K$. The valve is open allow the pressures to equalize, but the temperature of each container constant at its initial value. The final pressure in the two containers will be to

The maximum range of a projectile fired with some initial velocity is found to be 1000 metre, in the absence of wind and air resistance. The maximum height h reached by this projectile is

The ellipse $E_1 : \frac{x^2}{9} + \frac{y^2}{4}$ = 1 is inscribed in a rectangle R whose sides are parallel to the coordinate axes. Another ellipse $E_2$ passing through the point (0, 4) circumscribes the rectangle R. The eccentricity of the ellipse $E_2$ is

Stability of the species $ Li_2 , Li_2^- , \, \, and \, \, Li_2^+ $ increases in the order of

For which of the following compounds Kjeldahl method can be used to determine the percentage of Nitrogen ?

Satellite RNAs are present in some

Among flowers of Calotropis, tulip, Sesbania, Asparagus, Colchicum, sweet pea, Petunia, Indigofera, mustard, soybean, tobacco and groundnut, how many plants have corolla with valvate aestivation?

A beam of unpolarized light of intensity $I_0$ is passed through a polaroid $A$ and then through another polaroid $B$ which is oriented so that its principal plane makes an angle of 45$^{\circ}$ relative to that of $A$. The intensity of the emergent light is

A diode detector is used to detect an amplitude modulated wave of $60\%$ modulation by using a condenser of capacity $250$ picofarad in parallel with a load resistance $100$ $\Omega$. Find the maximum modulated frequency which could be detected by it.

Experimentally it was found that a metal oxide has formula $ M_{0.98}O. $ Metal $M$, present as $ M^{2+} $ and $ M^{3+} $ in its oxide.Fraction of the metal which exists as $ M^{3+} $ would be

How many grams of methyl alcohol should be added to $10$ litre tank of water to prevent its freezing at $268\, K$ ? $\left(K_{f} \, for\, water\, is \,1.86 K\, kg \, mol^{-1} \right)$

A uniform wire (Young?s modulus $2 \times 10^{11}\,Nm^{-2}$) is subjected to longitudinal tensile stress of $5 \times 10^{7}\,Nm^{-2}$. If the overall volume change in the wire is $0.02\%$, the fractional decrease in the radius of the wire is close to:

To establish an instantaneous current of $2 A$ through a $1 \mu F$ capacitor; the potential difference across the capacitor plates should be changed at the rate of :

Consider the following reaction, $xMnO_4^- + yC_2O_4^{2-}+zH^+ \rightarrow xMn^{2+}+2yCO_2 + \frac{z}{2}H_2O$ The values of x, y and z in the reaction are, respectively

Let $a_1, a_2, a_3,...$ be an $A.P$, such that $\frac{a_{1}+a_{2}+\ldots+a_{p}}{a_{1}+a_{2}+a_{3}+\ldots+a_{q}} = \frac{p^{3}}{q^{3}} ; p\ne q$ Then $\frac{a_{6}}{a_{21}}$ is equal to: