Chemical Compounds and Reactions

Carbon dioxide turns lime water milky.

Boiling point: -88.5^oC Melting point: -90.8^oC Relative density (water = 1): 1.23 at -89^oC Solubility in water (g/100 ml at 15^oC: 0.15) Vapour pressure (k Pa at 20^oC): 5150 Relative vapour density (air = 1): 1.53

Mn²⁺: 3d⁴, four unpaired electrons- violet

Manganese dioxide (MnO₂) is used in dry battery cells.

Metal deficiency defect is generally found in NiO.

Natural gas is called 'sour gas' when it contains significant amounts of hydrogen sulfide (H₂S). The sulfur content gives it corrosive properties and a rotten egg odor. Carbon (C), phosphorus (P), and arsenic (As) are not responsible for the sour designation.

Statement 1 is incorrect: Methane is known as marsh gas because it is formed by methanogenic organisms that can be found in marshy areas. Statement 2 is correct: Hydrogen sulphide and sulphur bacteria mostly smell like rotten eggs.

Yes, chalk is porous, so it absorbs water; as a result, after some time it becomes heavier and sinks.

Due to insufficient combustions of fuel, steel utensils turn black from the bottom.

Coloured glass for goggles contains ferrous oxide.

Oxides of potassium and magnesium turn litmus solution blue because potassium and magnesium are metals. Metals form basic oxides which turn litmus solution blue.

Silver chloride is insoluble in cold water but soluble in excess of ammonia solution.

Chalky white ppt of lead hydroxide is formed when excess of ammonia is passed through an aqueous solution of lead nitrate.

Both are coloured.

Ans : 3.