The Biuret test is not given by:

In the following circuit,$PN$-junction diodes $D_1, D_2$ and $D_3$ are ideal. For the following potentials of $A$ and $B$,find the correct increasing order of equivalent resistance between $A$ and $B$:
$(i) V_A = -10\,V, V_B = -5\,V$
$(ii) V_A = -5\,V, V_B = -10\,V$
$(iii) V_A = -4\,V, V_B = -12\,V$

If $x_1, x_2, \ldots, x_n$ are $n$ observations such that $\sum_{i=1}^n x_i^2 = 400$ and $\sum_{i=1}^n x_i = 80$,then the least value of $n$ is

The radius $R$ of the soap bubble is doubled under isothermal conditions. If $T$ is the surface tension of the soap bubble,the work done in doing so is given by: (in $\pi R^{2} T$)

Which of the following enzymes is not useful for the digestion of proteins?

Two polaroids are placed in the path of an unpolarized beam of intensity $I_0$ such that no light is emitted from the second polaroid. If a third polaroid,whose polarization axis makes an angle $\theta$ with the polarization axis of the first polaroid,is placed between these polaroids,then the intensity of light emerging from the last polaroid will be