Chemistry MCQs for NEET — Practice Questions with Answers

When a chiral center is produced in a reaction, it typically results in the formation of a racemic mixture, which is an equimolar mixture of the two enantiomers (dextrorotatory and laevorotatory forms). This is because the reaction does not preferentially produce one enantiomer over the other, leading to a mixture that is optically inactive as the rotations cancel each other out.

The given information suggests that the hydrocarbon molecule 'A' is a planar cyclic structure where all the carbon-carbon bonds are of equal length between 1.34 Å (which is typical for double bonds) and 1.54 Å (which is typical for single bonds). This implies that the bonds are likely to be somewhere in between, hinting at possible resonance structures. A common example fitting this description is benzene, which is a planar cyclic molecule with bond angles of $120^ ext{°}$ due to its $sp^2$ hybridized carbon atoms.

Dextrin is a carbohydrate that is not soluble in water and is tasteless. Other carbohydrates like lactose, fructose, and melitriose are soluble in water and have a taste.

An optically active compound that rotates plane-polarized light counterclockwise is known as levorotatory, denoted by '(-)'. Therefore, all the given options (levorotatory, (-), and all of the above) are correct. The correct answer is 'all of above'.

The anomeric carbon in the cyclic structure of glucose is the carbon that was the carbonyl carbon (C=O) in the linear form of the molecule. For glucose, this is carbon 1 ( ext{C}_1). When glucose cyclizes to form a ring (either as an α or β anomer), ext{C}_1 becomes the anomeric carbon.

The anomeric carbon in the cyclic structure of fructose is the carbon that was the carbonyl carbon (C=O) in the linear form of the molecule. For fructose, this is carbon 2 ( ext{C}_2). When fructose cyclizes to form a ring (either as an α or β anomer), ext{C}_2 becomes the anomeric carbon.