If all interior angles of a quadrilateral are in $AP$ and the common difference is $10^{\circ}$,then find the smallest angle in degrees.

Bithional is an example of

What is $Z$ in the following reaction sequence?
$C_6H_5NH_2$ $\xrightarrow[(i) NaNO_2 + HCl / 273 \ K]{(ii) H_3PO_2 + H_2O}$ $\xrightarrow[(iii) CO, HCl, \text{anhydrous } AlCl_3/CuCl]{} Z$

The maximum energy in the thermal radiation from a hot source occurs at a wavelength of $11 \times 10^{-5} \text{ cm}$. According to Wien's displacement law,the temperature of the source (on the Kelvin scale) will be $n$ times the temperature of another source (on the Kelvin scale) for which the wavelength at maximum energy is $5.5 \times 10^{-5} \text{ cm}$. The value of $n$ is:

In a book of $500$ pages,it is found that there are $250$ typing errors. Assume that Poisson law holds for the number of errors per page. Then,the probability that a random sample of $2$ pages will contain no error,is :

Which of the following is not correct?