Govt Exams
For first-order reaction, each half-life reduces concentration by 50%. After 1st half-life (10 min): 50% remains. After 2nd half-life (20 min): 25% remains = 1/4th. Total time = 2 × 10 = 20 minutes.
Cp - Cv = R = 8.314 J/(mol·K). Therefore, Cv = 29 - 8.314 ≈ 20.7 ≈ 20.8 J/(mol·K). This indicates a diatomic gas (Cp = 7/2 R, Cv = 5/2 R).
Kc depends only on temperature. Pressure, concentration changes, and catalysts do not alter Kc value—they shift equilibrium position but not the constant itself.
Diamond has a 3D tetrahedral covalent network structure with C-C bonds in all directions, while graphite has layered structure with weak van der Waals forces between layers
Cu²⁺ requires 2 electrons per atom. 1 Faraday = 1 mol of electrons; moles of Cu = 1/2 = 0.5 mol
H₂O has maximum boiling point due to strong hydrogen bonding compared to other hydrides in group 16
Color of reactants has no effect on reaction rate. Temperature, catalyst, and concentration all significantly affect reaction rate.
E°cell = E°cathode - E°anode = 0.34 - (-0.76) = 1.10 V
[H⁺] = [OH⁻] indicates a neutral solution. At 25°C, Kw = [H⁺][OH⁻] = 1 × 10⁻¹⁴, so pH = 7, pOH = 7 confirms neutrality.
In a galvanic cell, anode is where oxidation occurs (loss of electrons). The cathode is where reduction occurs (gain of electrons).