What is the coordination number of the metal in $[Co(en)_2Cl_2]^+$?

Let $\alpha$ and $\beta$ be the roots of the equation $px^2 + qx + r = 0$ (where $p \neq 0$). If $p, q, r$ are in $A.P.$ and $\frac{1}{\alpha} + \frac{1}{\beta} = 4$,then the value of $|\alpha - \beta|$ is

If $\int \frac{d x}{x(\log x-2)(\log x-3)}=I+C$,then $I$ is equal to

$DDT$ residues are rapidly passed through the food chain causing biomagnification because $DDT$ is:

Pure $Si$ at $500\, K$ has equal number of electron $(n_e)$ and hole $(n_h)$ concentrations of $1.5 \times 10^{16} \,m^{-3}$. Doping by indium increases $n_h$ to $4.5 \times 10^{22} \,m^{-3}$. The doped semiconductor is of

Which of the following salts gives a white precipitate with $AgNO_3$ solution and dilute $H_2SO_4$ solution,and also gives a green flame test?