The pair whose both species are used in antiacid medicinal preparation is

• NaHCO₃ and Mg(OH)₂

• Na₂CO₃ and Ca(HCO₃)₂

• Ca(HCO₃)₂ and Mg(OH)₂

• Ca(OH)₂ and NaHCO₃.

The charge required for the reduction of 1 mol of ${\mathrm{MnO}}_4^{-}$  to MnO₂ is

• 1 F

• 2 F

• 3 F

• 6 F

13.

The energy gaps (E_g) between valence band and conduction band for diamond, silicon and germanium are in the order

• E_g (diamond) > E_g (silicon) > E_g (germanium)

• E_g (diamond) <E_g (silicon) <E_g (germanium)

• E_g (diamond) = E_g (silicon)= E_g (germanium)

• E_g (diamond)> E_g (germanium)> E_g (silicon).

Among the following L-serine is

Among the following which one can have a meso form?

• CH₃CH(OH)CH(Cl)C₂H₅

• CH₃CH(OH)CH(OH)CH₃

• C₂H₅CH(OH)CH(OH)CH₃

• HOCH₂CH(Cl)CH₃

The major product obtained on the monobromination (with Br₂/FeBr₃) of the following compound A is

Assertion : [Co(NO₂)₃(NH₃)₃] does not show optical isomerism.

Reason : It has a plane of symmetry.

• If both assertion and reason are true and reason is the correct explanation of the assertion.

• If both assertion and reason are true but reason is not the correct explanation of the assertion.

• If assertion is true, but reason is false.

• Both assertion and reason are false statements.

Assertion: Silicones are hydrophobic in nature.

Reason: Si-O- Si linkages are moisture sensitive.

• If both assertion and reason are true and reason is the correct explanation of the assertion.

• If both assertion and reason are true but reason is not the correct explanation of the assertion.

• If assertion is true, but reason is false.

• Both assertion and reason are false statements.

Assertion: Diastereomers have different physical properties.

Reason : They are non-superimposable mirror images.

• If both assertion and reason are true and reason is the correct explanation of the assertion.

• If both assertion and reason are true but reason is not the correct explanation of the assertion.

• If assertion is true, but reason is false.

• Both assertion and reason are false statements.

Assertion: The presence ofnitro group facilitates nucleophilic substitution reactions in aryl halides.

Reason: The intermediate carbanion is stabilised due to the presence of nitro group.

• If both assertion and reason are true and reason is the correct explanation of the assertion.

• If both assertion and reason are true but reason is not the correct explanation of the assertion.

• If assertion is true, but reason is false.

• Both assertion and reason are false statements.