On heating `Pb(NO_3)_2` a brown gas is evolved which undergoes dimerization on cooling. Identify the gas.

On heating ammonium dichromate, the gas evolved is

When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.

Which gas is evolved on heating calcium carbonate?

A metal carbonate X, and a metal bicarbonate Y on reacting with an acid gives a gas which turns lime water milky. Identify the gas, compound X and Y.

When conc. H_2SO_4 was added to an unknown salt present in a test tube, a brown gas (A) was evolved. The gas intensified when copper turnings were also added into this test tube. On cooling the gas A changed into a colourless gas (B). Identify the gases (A) and (B).

When conc. H_2SO_4 was added to an unknown salt present in a test tube, a brown gas (A) was evolved. The gas intensified when copper turnings were also added into this test tube. On cooling the gas A changed into a colourless gas (B). Write the equations for the reactions involved.

From a certain apparatus, the diffusion rate of hydrogen has an average value of 28.7 cm^3 s^-1 . The diffusion of another gas under the same conditions is measured to have an average rate of 7.2 cm^3 s^-1 . Identify the gas

When a mixture of ammonium chloride and potassium dichromate are heated, a stable colourless gas (A) was evolved which did not support combustion but magnesium continued to burn in it. The gas (A) reacted with calcium carbide in an electric furnance forming a solid (B). The compound (B) was slowly hydrolysed by water forming an insoluble substance (C) and the solution of substance (D) which turned Nessler’s reagent brown. Identify (A) to (E) and give the reactions involved.

Salt ‘A’ commonly used in bakery products on heating gets converted into another salt ‘B’ which itself is used for removal of hardness of water and a gas ‘C’ is evolved. The gas ‘C’ when passed through lime water, turns it milky. Identify A, B and C.

Name two metals which react violently with cold water. Write any three observtations you would make when such a metals is dropped into water. How would you identify the gas evolved if any, during the reaction?