The work function of caesium is \(2.14\mathit{eV.}\) Find The wavelength of the incident light if the photo current is brought to zero by a stopping potential of \(0.06V\) .
Answer
The photo current is brought to zero, this happens when the maximum kinetic energy of photons becomes equal to the potential energy \(v_o\) by the stopping potential \(v_o\) i.e. \(h=6.62\times 10^{-34} \;Js\) \(e=1.6\times 10^{-19}C\) \(ev_o=\mathit{hv}-\phi_o=\frac{\mathit{hc}}{\lambda }-\phi_o\) \(\lambda =\frac{\mathit{hc}}{ev_o+\phi_o}\) \(=\frac{6.62\times 10^{-34}\times 3\times 10^8}{\left(1.6\times 10^{-19}\times 0.60\right)+\left(2.14\times 1.6\times 10^{-19}\right)}\) \(=4.54\times 10^{-7}\text{ m }\)
An aqueous solution of \(NaCl\) on electrolysis gives \(H_{2}(g),Cl_{2}(g)\) and \(NaOH\) according to the reaction. \(2Cl^{-}(aq)+2H_{2}O\rightleftharpoons 2OH^{-}(aq)+H_{2}(g)+Cl_{2}(g)\) A direct current of \(25 A\) with a current efficiency of \(62\% \) is passed through \(20 L \)of \(NaCl\) solution (\(20\% \)by weight). Write down the reactions taking place at the anode and cathode. How long will it take to produce \(1\ kg \) of \(Cl_{2}\) ? What will be the molarity of the solution with respect to hydroxide ion? (Assume no loss due to evaporation)
For the elementary reaction, \(M\to N\), the rate of disappearance of M increases by a factor of 8 upon doubling the concentration of M. The order of the reaction with respect to M is ( )
\( A\) and \( B\) are \( 2\) events such that \( P\left(A\right)=\frac{3}{4} \)and\( P\left(B\right)=\frac{5}{8}\). If \( x\) and \( y\) are the possible minimum and maximum values of \( P(A\cap\;B)\), then the value of \( a+b\) is ( )
Read the statement given carefully and state with reasons, if it is true or false : The average speed of a particle (defined as total path length divided by the time taken to cover the path) is either greater or equal to the magnitude of average velocity of the particle over the same interval of time.___
Consider angles \( \alpha =(2n+\frac{1}{2})\pi \pm\;A \;\;\;and\; \beta =m\pi +(-1{)}^{m}(\frac{\pi }{2}-A) where\;n,m\in\;I.\) Which of the following is not true? ( )
A. \( \alpha\;and\; \beta \) are always the same angles
B. \( \alpha\;and \;\beta \)are co-terminal angles
C. \( sin\alpha =sin\beta\;but\;cos\alpha \ne\;cos\beta \)
Given, \(E^0_{Cl_{2}/Cl^{-}}=1.36V,E^{0}_{Cr^{3+}/Cr}=-0.74V\) \(E^{0}_{Cr_{2}O^{2-}_{7}/Cr^{3+}}=1.33V,E^{0}_{MnO^{-}_{4}/Mn^{2+}}=1.51V\) Among the following, the strongest reducing agent is( )
For the non-stoichiometric reaction, \(2A +B \to C +D\), the following kinetic data were obtained in three separate experiments, all at \(298 \ K\). The rate law for the formation of \(C\) is( )
A line passes through \( \left(2,0\right).\) Then which of the following is not the slope of the line, for which its intercept between \( y=x-1\;and\;y=-x+1\) subtends a right angle at the origin? ( )