Metallurgy

The stability constant ( ) of a complex is the inverse of the dissociation constant ( ). Given the dissociation constant for [Cr(H O) ] is , the stability constant is the reciprocal:

The correct option is (D) : 2×10¹¹

Magnesite is a mineral composed of magnesium carbonate (MgCO₃) and is not an ore of iron. The ores of iron include Haematite (Fe₂O₃), Magnetite (Fe₃O₄), Siderite (FeCO₃), and Iron pyrites (FeS₂). Haematite and Magnetite are the most common and significant ores of iron.

The correct option is (A) : Magnesite

Lactose is a disaccharide composed of one molecule of -D-galactose and one molecule of -D-glucose. These two sugars are linked by a β-1,4-glycosidic bond, which is hydrolyzed by lactase in the human body.