In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is
CH₃OH(l) + 3/2O₂(g) → CO₂(g) + 2H₂O(l)
At 298 K standard Gibb’s energies of formation for CH₃OH(l), H₂O(l) and CO₂(g) are –166.2, –237.2 and –394.4 kJ mol^–1 respectively. If
standard enthalpy of combustion of methanol is –726 kJ mol^–1, efficiency of the fuel cell will be:

• 80%

• 97%

• 87%

• 87%

Which one of the following reactions of Xenon compounds is not feasible?

• XeO₃+ 6HF → XeF₆  + 3H₂O

• 3XeF₄ +6H₂O → Xe+XeO₃+ 12HF+ 1.5O₂

• 2XeF₂ + 2H₂O → 2Xe + 4HF +O₂

• 2XeF₂ + 2H₂O → 2Xe + 4HF +O₂

Using MO theory predict which of the following species has the shortest bond length?

• O₂²⁺

• O₂⁺

• O₂⁻

• O₂⁻

Calculate the wavelength (in nanometer) associated with a proton moving at 1.0 × 10³ ms^–1
(Mass of proton = 1.67 × 10^–27 kg and h = 6.63 ×10^–34Js)

• 0.032 nm

• 0.40 nm

• 2.5 nm

• 2.5 nm

5.

The set representing the correct order of ionic radius is

• Li⁺> Be²⁺> Na⁺> Mg²⁺

• Na⁺>Li⁺>Mg²⁺> Be²⁺

• Li⁺>Na⁺ > Mg²⁺ > Be²⁺

• Li⁺>Na⁺ > Mg²⁺ > Be²⁺

In an atom, an electron is moving with a speed of 600m/s with an accuracy of 0.005%. Certainty with which the position of the electron can be located is ( h = 6.6 x10^-34 kgm2s^-1 mass of electron, em= 9.1 x10^-31kg)

• 1.52 x 10^-4m

• 5.10 x 10^-3m

• 1.92 x 10^-3m

• 1.92 x 10^-3m

The bond dissociation energy of B–F in BF3 is 646 kJ 1 mol⁻ whereas that of C-F in CF₄ is 515 kJ 1 mol⁻.The correct reason for higher B-F bond dissociation energy as compared to that of C-F is

• Smaller size of B-atom as compared to that of C- atom

• Stronger σ bond between B and F in BF₃ as compared to that between C and F in CF₄

• Significant pπ - pπ interaction between B and F in BF whereas there is no possibility of such 3 interaction between C and F in CF₄ 

• Significant pπ - pπ interaction between B and F in BF whereas there is no possibility of such 3 interaction between C and F in CF₄ 

The IUPAC name of neopentane is

• 2-methylbutane

• 2, 2-dimethylpropane

• 2-methylpropane

• 2-methylpropane

Knowing that the Chemistry of lanthanoids (Ln) is dominated by its +3 oxidation state, which of the following statements in incorrect

• The ionic sizes of Ln (III) decrease in general with increasing atomic number.

• Ln (III) compounds are generally colourless.

• Because of the large size of the Ln (III) ions, the bonding in its compounds is predominantly ionic in character

• Because of the large size of the Ln (III) ions, the bonding in its compounds is predominantly ionic in character

A liquid was mixed with ethanol and a drop of concentrated H₂SO₄ was added. A compound with a fruity smell was formed. The liquid was:

• CH₃OH

• HCHO

• CH₃COCH₃

• CH₃COCH₃