Live practice

The Mn3+ ion is unstable in solution and undergoes disproportionation to give Mn2+, MnO2, and H+ ion. Give a balanced ionic equation for the reaction.

Equilibrium constant, Kc for the reaction 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?

Comment on NO(g) stability using ΔfH°(NO)=+90 kJ mol⁻¹ and NO+1/2O₂→NO₂, ΔH°=−74 kJ mol⁻¹.

Why is methane tetrahedral rather than square planar?

Predict the sign and relative magnitude of the second electron-gain enthalpy of oxygen.

An electron has mass 9.1 × 10⁻³¹ kg and kinetic energy 3.0 × 10⁻²⁵ J. Calculate its de Broglie wavelength.

The same masses of nitrogen combine separately with \(16\,\mathrm{g}\), \(32\,\mathrm{g}\) and \(40\,\mathrm{g}\) of oxygen in several nitrogen oxides. (a) Identify and state the chemical-combination law illustrated. (b) Complete these conversions: (i) \(1\,\mathrm{km}\) into mm and pm; (ii) 1 mg into kg and ng; (iii) 1 mL into L and dm³.

Two \(100\,\mathrm{kg}\) spheres have centres \(1.0\,\mathrm{m}\) apart. Find

A \(0.25\,\mathrm{kg}\) stone moves in a horizontal circle of radius \(1.5\,\mathrm{m}\) at 40 rev min⁻¹. Find the tension. Also find the greatest speed if the string withstands 200 N.

The segment from (1,0) to (2,3) is divided internally in the ratio 1:n. Find the line through the division point perpendicular to that segment.