Board exam

Which one of the following first row transition elements is expected to have the highest third ionization enthalpy ?

1. AIron (Z = 26)
2. BManganese (Z = 25)
3. CChromium (Z = 24)
4. DVanadium (Z = 23)

Two among the three components of DNA are β-D-2-deoxyribose and a heterocyclic base. The third component is :

1. AAdenine
2. BPhosphoric acid
3. CSulphuric acid
4. DUracil

Acetic acid reacts with PCl₅ to give :

1. ACl–CH₂–COCl
2. BCl–CH₂–COOH
3. CCH₃–COCl
4. DCCl₃–COOH

The formation of cyanohydrin from an aldehyde is an example of :

1. Anucleophilic addition
2. Belectrophilic addition
3. Cnucleophilic substitution
4. Delectrophilic substitution

The reaction of an alkyl halide with sodium alkoxide forming ether is known as :

1. AWurtz reaction
2. BReimer-Tiemann reaction
3. CWilliamson synthesis
4. DKolbe reaction

The correct order of the ease of dehydration of the following alcohols by the action of conc. H₂SO₄ is :

1. A(CH₃)₃C–OH > (CH₃)₂CH–OH > CH₃CH₂–OH
2. B(CH₃)₂CH–OH > CH₃CH₂–OH > (CH₃)₃C–OH
3. CCH₃CH₂–OH > (CH₃)₂CH–OH > (CH₃)₃C–OH
4. D(CH₃)₂CH–OH > (CH₃)₃C–OH > CH₃CH₂–OH

Which functional groups of glucose interact to form cyclic hemiacetal leading to pyranose structure ?

1. AAldehyde group and hydroxyl group at C 4
2. BAldehyde group and hydroxyl group at C 5
3. CKetone group and hydroxyl group at C 4
4. DKetone group and hydroxyl group at C 5

Assertion (A) : When NaCl is added to water a depression in freezing point is observed. Reason (R) : NaCl undergoes dissociation in water.

1. ABoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
2. BBoth Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
3. CAssertion (A) is true, but Reason (R) is false.
4. DAssertion (A) is false, but Reason (R) is true.