21.

Which of the following is wrong statement?

• Ni(CO)₄ has oxidation number +4 for Ni

• Ni(CO)₄ has zero oxidation number for Ni

• Ni is metal

• CO is gas

In [NiCl₄]^2-, the number of unpaired electrons, are

• 4

• 2

• 3

• 5

Which carbocation is most stable ?

• CH₃CH${}_2^{+}$

• C${\mathrm{H}}_3^{+}$

• C₆H₅C${\mathrm{H}}_2^{+}$

• CH₃CH₂C${\mathrm{H}}_2^{+}$

CH₃C(CH₂CH₃) = CH(CH₃) $\underset{{\mathrm{H}}_2}{\overset{\mathrm{catalyst}}{\to }}$ X. No. of optical isomer possible will be

• 2

• 4

• 0

• 3

H₂C₂O₄ + KMnO₄ in acidic medium reacts to have change in oxidation number of Mn from

• 7 to 5

• 2 to 7

• 5 to 7

• 7 to 2

NaOH / H⁺ reacts with

• C₆H₅OCH₃

• CH₃OH

• CH₃COCH₃

• C₂H₅OH

Butyne-1 and butyne-2 can be distinguished by

• H₂SO₄

• AgNO₃ + NH₄OH

• K₂Cr₂O₇

• NH₄OH

Most acidic is

• CH₃COOH

• C₆H₅CH₂COOH

• HCOOH

• CH₃CH₂COOH

Carborandum is

• Al₂O₃

• AlCl₃

• CuCO₃

• SiC

Frenkel and Schottky defects are

• nucleus defects

• non-crystal defects

• crystal defects

• nuclear defects