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

Explain with the help of suitable example polar covalent bond.

Arrange the bonds in order of increasing ionic character in the molecules: LiF, K₂O, N₂, SO₂ and ClF₃.

Which out of NH₃ and NF₃ has higher dipole moment and why?

At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?

The pressure of 1 g of an ideal gas A at 27 °C is found to be 2 bar. When 2 g of another ideal gas B is introduced in the same flask at the same temperature the pressure becomes 3 bar. Find a relationship between their molecular masses.

The drain cleaner, Drainex contains small bits of aluminum which react with caustic soda to produce dihydrogen. What volume of dihydrogen at 20 °C and one bar will be released when 0.15g of aluminum reacts?

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?

The enthalpies of all elements in their standard states are ______.

The reaction of cyanamide, NH₂CN_(s), with dioxygen was carried out in a bomb calorimeter, and ΔU was found to be −742.7 kJ mol⁻¹ at 298 K. Calculate enthalpy change for the reaction at 298 K.

\[\ce{NH_2 CN(g) + 3/2 O_2(g) -> N_2(g) + CO_2(g) + H_2O(l)}\]

Calculate the enthalpy change on freezing of 1.0 mol of water at 10.0°C to ice at - 10.0°C. Δ_fusH = 6.03 kJ mol^-1 at 0°C.

C_p[H₂O(l)] = 75.3 J mol^-1 K^-1

C_p[H₂O(s)] = 36.8 J mol^-1 K^-1

Enthalpy of combustion of carbon to CO₂ is –393.5 kJ mol^–1. Calculate the heat released upon formation of 35.2 g of CO₂ from carbon and dioxygen gas.

Enthalpies of formation of CO_(g), CO_2(g), N₂O_(g) and N₂O_4(g) are -110 kJ mol^-1, - 393 kJ mol^-1, 81 kJ mol^-1 and 9.7 kJ mol^-1 respectively. Find the value of Δ_rH for the reaction:

\[\ce{N2O_{4(g)} + 3CO_{(g)} → N2O_{(g)} + 3CO_{2(g)}}\]

Given

\[\ce{N_{2(g)} + 3H_{2(g)} -> 2NH_{3(g)}}\]; Δ_rH^θ = –92.4 kJ mol^–1

What is the standard enthalpy of formation of NH₃ gas?

Calculate the standard enthalpy of formation of CH₃OH_(l) from the following data:

\[\ce{CH3OH_{(l)} + 3/2 O2_{(g)} →CO_{2(g)} + 2H2O_{(l)}}\] ; Δ_rH^θ = –726 kJ mol^–1

\[\ce{C_{(g)} + O_{2(g)} →CO_{2(g)}}\] ; Δ_cH^θ = –393 kJ mol^–1

\[\ce{H_{2(g)} +1/2 O_{2(g)} → H2O_{(l)}}\] ; Δ_fH^θ = –286 kJ mol^–1.

Calculate the entropy change in surroundings when 1.00 mol of H₂O_(l) is formed under standard conditions. Δ_fH^θ = –286 kJ mol^–1.

A mixture of 1.57 mol of N₂, 1.92 mol of H₂ and 8.13 mol of NH₃ is introduced into a 20 L reaction vessel at 500 K. At this temperature, the equilibrium constant, K_c for the reaction 

\[\ce{N2 (g) + 3H2 (g)⇌2NH3 (g)}\] is 1.7 × 10²

Is the reaction mixture at equilibrium? If not, what is the direction of the net reaction?

Write IUPAC name of the product obtained by the ozonolysis of the following compound: 

1-Phenylbut-1-ene

Write the resonance structure of `"CO"_3^(2-)`.

Write the resonance structure of `"HCO"_3^(-)`.