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

What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition n = 4 to n = 2 of He⁺ spectrum?

Emission transitions in the Paschen series end at orbit n = 3 and start from orbit n and can be represented as v = 3.29 × 10¹⁵ (Hz) [1/3² – 1/n²]

Calculate the value of n if the transition is observed at 1285 nm. Find the region of the spectrum.

Calculate the wavelength for the emission transition if it starts from the orbit having radius 1.3225 nm and ends at 211.6 pm. Name the series to which this transition belongs and the region of the spectrum.

Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume?

\[\ce{PCl5 (g) ⇌ PCl3 (g) + Cl2 (g)}\]

Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume?

\[\ce{CaO (s) + CO2 (g) ⇌ CaCO3 (s)}\]

Two students performed the same experiment separately and each one of them recorded two readings of mass which are given below. Correct reading of mass is 3.0 g. On the basis of given data, mark the correct option out of the following statements.

Calculate the average atomic mass of hydrogen using the following data:

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.