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

What is the experimental evidence in support of the idea that electronic energies in an atom are quantized?

Which of the following elements can show covalency greater than 4?

(i) Be

(ii) P

(iii) S

(iv) B

Predict the hybridisation of each carbon in the molecule of organic compound given below. Also indicate the total number of sigma and pi bonds in this molecule.

\[\begin{array}{cc}
\phantom{.............}\ce{O}\phantom{............}\ce{O}\phantom{}\\
\phantom{.............}||\phantom{...........}//\phantom{.}\\
\ce{CH ≡ C - C - CH2 - C}\\
\phantom{........................}\backslash\\
\phantom{.............................}\ce{OH}
\end{array}\]

A gas that follows Boyle’s law, Charle’s law and Avogadro’s law is called an ideal gas. Under what conditions a real gas would behave ideally?

One of the assumptions of kinetic theory of gases states that “there is no force of attraction between the molecules of a gas.” How far is this statement correct? Is it possible to liquefy an ideal gas? Explain.

One of the assumptions of kinetic theory of gases is that there is no force of attraction between the molecules of a gas. State and explain the evidence that shows that the assumption is not applicable for real gases.

During complete combustion of one mole of butane, 2658 kJ of heat is released. The thermochemical reaction for above change is ______.

\[\ce{∆_f U^Θ}\] of formation of \[\ce{CH4 (g)}\] at certain temperature is – 393 kJ mol^–1. The value of \[\ce{∆_f H^Θ}\] is ______.

On the basis of thermochemical equations (a), (b) and (c), find out which of the algebric relationships given in options (i) to (iv) is correct.

(a) \[\ce{C (graphite) + O2 (g) -> CO2 (g) ; ∆_rH = xkJ mol^{-1}}\]

(b) \[\ce{C (graphite) + 1/2 O2 (g) -> CO (g) ; ∆_rH = ykJ mol^{-1}}\]

(c) \[\ce{CO (g) + 1/2 O2 (g) -> CO2 (g) ; ∆_r H = zkJ mol^{-1}}\]

The standard molar entropy of \[\ce{H2O (l)}\] is 70 JK^–1 mol^–1. Will the standard molar entropy of \[\ce{H2O (s)}\] be more, or less than 70 JK^–1 mol^–1?

The molar enthalpy of vapourisation of acetone is less than that of water. Why?

If the combustion of 1g of graphite produces 20.7 kJ of heat, what will be molar enthalpy change? Give the significance of sign also.

Derive the relationship between ∆H and ∆U for an ideal gas. Explain each term involved in the equation.

Which of the following statements is incorrect?

The pH of neutral water at 25°C is 7.0. As the temperature increases, ionisation of water increases, however, the concentration of \[\ce{H+}\] ions and \[\ce{OH-}\] ions are equal. What will be the pH of pure water at 60°C?

On the basis of Le Chatelier principle explain how temperature and pressure can be adjusted to increase the yield of ammonia in the following reaction.

\[\ce{N2 (g) + 3H2 (g) ⇌ 2NH3 (g) ∆H = - 92.38 kJ mol^{-1}}\]

What will be the effect of addition of argon to the above reaction mixture at constant volume?

Why is hydrogen peroxide stored in wax-lined bottles?

Assertion (A): Some metals like platinum and palladium, can be used as storage media for hydrogen.

Reason (R): Platinum and palladium can absorb large volumes of hydrogen.

Sodium forms a crystalline ionic solid with dihydrogen. The solid is nonvolatile and non-conducting in nature. It reacts violently with water to produce dihydrogen gas. Write the formula of this compound and its reaction with water. What will happen on electrolysis of the melt of this solid.

Quartz is extensively used as a piezoelectric material, it contains ______.