Identify the reagent used in the following reaction.
Benzoic acid $\stackrel{\text{Reagent}}{\Delta}$ Benzoyl chloride + Phosphorous oxychloride + Hydrogen chloride

The equation of the directrix of the parabola ${y^2} + 4y + 4x + 2 = 0$ is

In a series $LCR$ circuit,what will be the nature of the circuit for frequencies higher than the resonance frequency?

$A$ reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by $62^{\circ} C$,the efficiency of the engine is doubled. The temperatures of the source and sink are:

Which of the following is not a characteristic of life?

The mean of five observations is $4$ and their variance is $5.2$. If three of these observations are $1, 2$ and $6$,then the other two are