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

The density of a gas is found to be 5.46 g/dm³ at 27 °C at 2 bar pressure. What will be its density at STP?

How much time would it take to distribute one Avogadro number of wheat grains, if 10¹⁰ grains are distributed each second?

Why is Wurtz reaction not preferred for the preparation of alkanes containing odd number of carbon atoms? Illustrate your answer by taking one example

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as:

\[\ce{CH3COOH (l) + C2H5OH (l) ⇌ CH3COOC2H5 (l) + H2O (l)}\]

Write the concentration ratio (reaction quotient), Qc, for this reaction (note: water is not in excess and is not a solvent in this reaction).

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as:

\[\ce{CH3COOH (l) + C2H5OH (l) ⇌ CH3COOC2H5 (l) + H2O (l)}\]

At 293 K, if one starts with 1.00 mol of acetic acid and 0.18 mol of ethanol, there is 0.171 mol of ethyl acetate in the final equilibrium mixture. Calculate the equilibrium constant.

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as:

\[\ce{CH3COOH (l) + C2H5OH (l) ⇌ CH3COOC2H5 (l) + H2O (l)}\]

Starting with 0.5 mol of ethanol and 1.0 mol of acetic acid and maintaining it at 293 K, 0.214 mol of ethyl acetate is found after sometime. Has equilibrium been reached?

Suggest a reason as to why CO is poisonous.

Explain the following reaction.

CO is heated with ZnO.

Equilibrium constant, K_c for the reaction 

\[\ce{N2 (g) + 3H2 (g) ⇌ 2NH3 (g)}\] at 500 K is 0.061.

At a particular time, the analysis shows that composition of the reaction mixture is 3.0 mol L^–1 N₂, 2.0 mol L^–1 H₂ and 0.5 mol L^–1 NH₃. Is the reaction at equilibrium? If not in which direction does the reaction tend to proceed to reach equilibrium?

What causes the temporary and permanent hardness of water?

Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.

The number of atoms present in one mole of an element is equal to Avogadro number. Which of the following element contains the greatest number of atoms?

45.4 L of dinitrogen reacted with 22.7 L of dioxygen and 45.4 L of nitrous oxide was formed. The reaction is given below:

\[\ce{2N2(g) + O2(g) -> 2N2O(g)}\]

Which law is being obeyed in this experiment? Write the statement of the law?

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.

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