Science (English Medium) Class 11 - CBSE Question Bank Solutions for Chemistry

Ionic radii vary in

(i) inverse proportion to the effective nuclear charge.

(ii) inverse proportion to the square of effective nuclear charge.

(iii) direct proportion to the screening effect.

(iv) direct proportion to the square of screening effect.

Which of the following species has tetrahedral geometry?

Which of the following statements are not correct?

(i) \[\ce{NaCl}\] being an ionic compound is a good conductor of electricity in the solid state.

(ii) In canonical structures there is a difference in the arrangement of atoms.

(iii) Hybrid orbitals form stronger bonds than pure orbitals.

(iv) \[\ce{VSEPR}\] Theory can explain the square planar geometry of \[\ce{XeF4}\].

Explain why \[\ce{CO^{2–}3}\] ion cannot be represented by a single Lewis structure. How can it be best represented?

Draw the resonating structure of ozone molecule

Draw the resonating structure of nitrate ion

When hydrochloric acid is added to cobalt nitrate solution at room temperature, the following reaction takes place and the reaction mixture becomes blue. On cooling the mixture it becomes pink. On the basis of this information mark the correct answer.

\[\ce{\underset{(pink)}{[Co(H2O)6]^{3+}} (aq) + 4Cl- (qa) ⇌ \underset{(blue)}{[CoCl4]^{2-}} (aq) + 6H2O (l)}\]

Why does hard water not form lather with soap?

Arrange the following alkyl halides in decreasing order of the rate of β– elimination reaction with alcoholic KOH.

An alkyl halide C₅H₁₁Br (A) reacts with ethanolic KOH to give an alkene ‘B’, which reacts with Br₂ to give a compound ‘C’, which on dehydrobromination gives an alkyne ‘D’. On treatment with sodium metal in liquid ammonia one mole of ‘D’ gives one mole of the sodium salt of ‘D’ and half a mole of hydrogen gas. Complete hydrogenation of ‘D’ yields a straight-chain alkane. Identify A, B, C and D. Give the reactions invovled.

If 10 volumes of dihydrogen gas reacts with five volumes of dioxygen gas, how many volumes of water vapour would be produced?

Energy of an electron in the ground state of the hydrogen atom is –2.18 × 10^–18 J. Calculate the ionization enthalpy of atomic hydrogen in terms of J mol^–1.
Hint: Apply the idea of mole concept to derive the answer.

Among the second period elements the actual ionization enthalpies are in the

order Li < B < Be < C < O < N < F < Ne.

Explain why Be has higher Δ_iH than B?

Among the second period elements the actual ionization enthalpies are in the

order Li < B < Be < C < O < N < F < Ne.

Explain why O has lower Δ_iH than N and F?

How would you explain the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium?

What are the various factors due to which the ionization enthalpy of the main group elements tends to decrease down a group?

The first ionization enthalpy values (in kJmol^–1) of group 13 elements are:-

How would you explain this deviation from the general trend?

Would you expect the first ionization enthalpies for two isotopes of the same element to be the same or different? Justify your answer.

Which one of the following statements is incorrect in relation to ionization enthalpy?

Calculate the wavelength, frequency and wave number of a light wave whose period is 2.0 × 10^-10s.