Green flame with Blue centre is given by Cupric salts.
Crimson red - \(Sr^{2+ }\)
Brick red - \(Ca^{2+ }\)
Green - \(Ba^{2+ }\)
Hence, the correct option is (A): \(Cu^{2+}\)
The correct stability order of the following diazonium salts is: 
Choose the correct answer from the options given below:
Arrange the following carbanions in the decreasing order of stability:
I. $p$-$\mathrm{Br{-}C_6H_4{-}CH_2^-}$
II. $\mathrm{C_6H_5{-}CH_2^-}$
III. $p$-$\mathrm{CH_3O{-}C_6H_4{-}CH_2^-}$
IV. $p$-$\mathrm{CHO{-}C_6H_4{-}CH_2^-}$
V. $p$-$\mathrm{CH_3{-}C_6H_4{-}CH_2^-}$
Choose the correct answer from the options given below:

Two circular discs of radius \(10\) cm each are joined at their centres by a rod, as shown in the figure. The length of the rod is \(30\) cm and its mass is \(600\) g. The mass of each disc is also \(600\) g. If the applied torque between the two discs is \(43\times10^{-7}\) dyne·cm, then the angular acceleration of the system about the given axis \(AB\) is ________ rad s\(^{-2}\).

A sparingly soluble salt is so-called because when it is dissolved into a solvent, only a very small amount of the salt goes into the solution, and most of it remains undissolved. The solution becomes saturated with that little amount of salt dissolved, and the salt immediately dissociates into its ions.
Quantitatively, a solute is sparingly soluble if 0.1g (or less than that) of the solute is dissolved in 100ml of the solvent.