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Sodium salt of an organic acid ‘X’ produces effervescence with conc. H₂SO₄. ‘X’ reacts with the acidified aqueous CaCl₂ solution to give a white precipitate which decolourises the acidic solution of KMnO₄. ‘X’ is :

1) CH3COONa 2) Na2C2O4 3) C6H5COONa 4) HCOONa Answer: (2)... View Article

In the following reactions, ZnO is respectively acting as a/an :

(a) ZnO + Na2O → Na2ZnO2 (b) ZnO + CO2 → ZnCO3 1) acid and acid 2) acid and base 3) base and acid 4) base and base Answer: (2) In... View Article

The products obtained when chlorine gas reacts with cold and dilute aqueous NaOH are :

1) Cl− and ClO− 2) Cl− and ClO2 − 3) ClO− and ClO3− 4) ClO2− and ClO3 Answer: (1)... View Article

The group having isoelectronic species is :

1) O2−, F−, Na, Mg2+ 2) O−, F−, Na+, Mg2+ 3) O2−, F−, Na+, Mg2+ 4) O−, F−, Na, Mg+ Answer: (3) Mg2+, Na+, O2– and F– all have 10... View Article

A water sample has ppm level concentration of following anions

F- = 10; SO2-4 = 100; NO3- = 50 The anion/anions that make/makes the water sample unsuitable for drinking is/ are : 1) only F− 2) only SO2-4... View Article

Which of the following reactions is an example of a redox reaction?

1) XeF6 + H2O → XeOF4 + 2HF 2) XeF6 + 2H2O → XeO2 F2 + 4HF 3) XeF4 + O2 F2 → XeF6 + O2 4) XeF2 + PF5 → [XeF]+ PF6 − Answer: (3) Xe is... View Article

Which of the following species is not paramagnetic?

1) O2 2) B2 3) NO 4) CO Answer: (4) CO has 14 electrons (even) ∴ it is diamagnetic. NO has 15e– (odd) ∴ it is paramagnetic and has 1... View Article

Both lithium and magnesium display several similar properties due to the diagonal relationship; however, the one which is incorrect, is :

1) both form nitrides 2) nitrates of both Li and Mg yield NO2 and O2 on heating 3) both form basic carbonates 4) both form soluble... View Article

pK_aof a weak acid (HA) and pK_b of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is :

1) 7.0 2) 1.0 3) 7.2 4) 6.9 Answer: (4) pH = 7 + [(1 / 2) (pKa - pKb)] = 7 + (1 / 2) [3.2 - 3.4] = 6.9... View Article

Two reactions R₁ and R₂ have identical pre-exponential factors. The activation energy of R₁ exceeds that of R₂ by 10 kJ mol⁻¹. If k₁ and k₂ are rate constants for reactions R₁ and R₂ respectively at 300 K, then ln (k₂/k₁) is equal to (R = 8.314 J mol⁻¹K⁻¹)

1) 6 2) 4 3) 8 4) 12 Answer: (2)... View Article

The radius of the second Bohr orbit for the hydrogen atom is : (Planck’s Constant. h = 6.6262 × 10⁻³⁴ Js; the mass of electron = 9.1091 × 10⁻³¹ kg; charge of electron e = 1.60210 × 10⁻¹⁹ C; permittivity of vacuum ∈₀= 8.854185 × 10⁻¹² kg⁻¹m⁻³A²)

1) 0.529 Å 2) 2.12 Å 3) 1.65 Å 4) 4.76 Å Answer: (2) r = a0 (n2 / Z) = 0.529 × 4 = 2.12 Å... View Article

The freezing point of benzene decreases by 0.45^oC when 0.2 g of acetic acid is added to 20 g of benzene. If acetic acid associates to form a dimer in benzene, percentage association of acetic acid in benzene will be : (K_f for benzene = 5.12 K kg mol⁻¹)

1) 74.6% 2) 94.6% 3) 64.6% 4) 80.4% Answer: (2) 0.45 = i (5.12) [(0.2 / 60) / 20] * 1000 i = 0.527 2CH3 COOH ⇋ [CH3 COOH]2 (1 - α) α... View Article

Which is the strongest reducing agent

1) Cr3+ 2) Cl− 3) Cr 4) Mn2+ Answer: (3) Positive E° is for Cr, hence it is the strongest reducing agent.... View Article

A metal crystallises in a face centred cubic structure. If the edge length of its unit cell is ‘a’, the closest approach between two atoms in metallic crystal will be:

1) √2 a 2) a/√2 3) 2a 4) 2√2 a Answer: (2) In FCC, one of the faces is like By △ABC, 2a2 = 16r2 r2 = (1 / 8) a2 r = 1 / 2√2 a... View Article

The Tyndall effect is observed only when the following conditions are satisfied:

(a) The diameter of the dispersed particles is much smaller than the wavelength of the light used. (b) The diameter of the dispersed particle is... View Article

∆U is equal to :

1) Adiabatic work 2) Isothermal work 3) Isochoric work 4) Isobaric work Answer: (1) For adiabatic process, q = 0 As per 1st law of... View Article

1 gram of a carbonate (M₂CO₃) on treatment with excess HCl produces 0.01186 moles of CO₂. The molar mass of M₂CO₃ in g mol⁻¹ is :

1) 118.6 2) 11.86 3) 1186 4) 84.3 Answer: (4) M2CO3 + 2HCl → 2MCl + H2O + CO2 = 84.3 g/mol... View Article

Given C_(graphite)+ O₂ (g) → CO₂ (g) ; ∆_rH^o = −393.5 kJ mol⁻¹

H2 (g) + [1 / 2] O2 (g) → H2O (l) ; ∆r Ho= −285.8 kJ mol−1 CO2 (g) + 2H2O(l) → CH4 (g) + 2O2 (g) ; ∆r Ho = +890.3 kJ mol−1 Based on the... View Article

Consider a compound slab consisting of two different materials having equal lengths, thicknesses and thermal conductivities K and 2K respectively. The equivalent thermal conductivity of the slab is (A) √2K (B) 3K (C) (4/3)K (D) (2/3)K

The thermal resistances can be added as they are in series. Here the width of the combined slab is twice the width of individual slab Hence, we... View Article

The amount of heat produced in a wire depends on its materials (A) Length (B) Thickness (C) Length and thickness (D) None of these

Amount of heat produced in a wire = I2R Where R is resistance of wire I is current through wire As resistance of wire R ∝ L/A Hence, The... View Article