List of practice Questions

An $LED$ is constructed from a $pn$ junction based on a certain semi-conducting material whose energy gap is $1.9\, eV$. Then the wavelength of the emitted light is
The masses of three copper wires are in the ratio $2 : 3 : 5$ and their lengths are in the ratio $5 : 3 : 2$ .Then, the ratio of their electrical resistances is
In a potentiometer experiment, the balancing length of a cell is $560\, cm$. When an external resistance of $10 \, \Omega$ is connected in parallel to the cell, the balancing length changes by $60 \,cm$.The internal resistance of a cell is
Point out incorrect stability order
The chemical composition of slag formed during the smelting process in the extraction of copper is
The molarity of $NO_3^-$ in the solution after $2L$ of $3M \, AgNO_3$ is mixed with $3L$ of $1M \, BaCl_2$ is
If the equilibrium constant for ${ N2(g) + O2(g) <=> 2NO(g)}$ is K, the equilibrium constant for ${ \frac{1}{2} N_2 (g) + \frac{1}{2} O_2 (g) <=> NO(g) }$ will be :
The solution set of the inequation $\frac {x^2+6x-7}{|x+4|}<0$ is
The value of $\sin ^{-1} (\frac {2 \sqrt {2}}{3})+\sin^{-1} (\frac {1}{3}) $ is equal to
What is the pH of the resulting solution when equal volumes of $0.1\, M \,NaOH$ and $0.01\, M$ $HCl$ are mixed ?
The order of differential equation of all circles of given radius $'a'$ is _____
If $x$ is real, then the minimum value of $x^2 - 8x+17 $ is
Which of the following is a gymnosperm in which vessels are found?
The average power dissipated in a pure inductor is
The electrolyte having maximum flocculation value for $AgI/Ag^+$ sol is
The two electrons have the following set of quantum numbers: $P = 3 , 2 , - 2 , + \frac {1}{2}$ $Q = 3,0,0,+\frac {1}{2}$ Which of the following statement is true ?
How many ions per molecule are produced in the solution when Mohr salt is dissolved in excess of water ?
In $H_2 - O_2$ fuel cell the reaction occurring at cathode is
On heating with concentrated $NaOH$ solution in an inert atmosphere of $CO_2$ white phosphorous gives a gas. Which of the following statement is incorrect about the gas ?
Which one of the following electrolytes has the same value of van't Hoff's factor (i) as that of $ {Al_2(SO_4)_3}$ (if all are 100% ionised) ?
Gastric juice of infants contains
The equation of the plane which bisects the line segment joining the points $(3, 2, 6)$ and $(5,4, 8)$ and is perpendicular to the same line segment, is
$ : CCl_2 $ is
For a simple pendulum, a graph is plotted between its Kinetic Energy (KE) and Potential Energy (PE) against its displacement d. Which one of the following represents these correctly? (graphs are schematic and not drawn to scale)
Which one of the following is correct?