Nitrobenzene on reduction with zinc and $NH_4Cl$ gives

In a floral formula,what does the notation $(K)$ denote?

If $\alpha, \beta, \gamma$ are the roots of the equation $x^3+4x+1=0$,then $(\alpha+\beta)^{-1}+(\beta+\gamma)^{-1}+(\gamma+\alpha)^{-1}$ is equal to

Which of the following metals becomes passive towards concentrated $HNO_3$?

Which of the following is known as the $ \text{Christmas Tree} $?

Which of the following contains both ionic and covalent bonds?