| List I (Anion) | List II (gas evolved on reaction with dil \(H_2SO_4\)) | ||
|---|---|---|---|
| A. | \(CO_3^{ 2−}\) | I. | Colourless gas which turns lead acetate paper black. |
| B. | \(S^{2–}\) | II. | Colourless gas which turns acidified potassium dichromate solution green |
| C. | \(SO_3^{ 2−}\) | III. | Brown fumes which turns acidified KI solution containing starch blue. |
| D. | \(NO_2^{−}\) | IV. | Colourless gas evolved with brisk effervescence, which turns lime water milky. |
\(CO_3^{ 2−}\): On action of diluted sulphuric acid, \(CO_2\) gas is released which turns lime water milky.
\(S ^{2-}:\) On action of diluted sulphuric acid, \(H_2S\) gas is released which turns lead acetate paper black.
\(SO_3^{ 2−}\): On action of diluted \( H_2SO_4, SO_2\) gas is evolved which turns acidified potassium dichromate solution green.
\(NO^{2−}\): On action of dil \(H_2SO_4, NO_2\) gas is evolved which turns Kl solution contain starch blue.
\(Hence,\) the correct option is (D): \(A-IV, B-I, C-II, D-III\)
In the given figure, the blocks $A$, $B$ and $C$ weigh $4\,\text{kg}$, $6\,\text{kg}$ and $8\,\text{kg}$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is ___ N.
(Given: $g = 10\,\text{m s}^{-2}$) 
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\(^{-2}\).

The gas laws were developed at the end of the 18th century, when scientists began to realize that relationships between pressure, volume and temperature of a sample of gas could be obtained which would hold to approximation for all gases.