GATE Environmental Chemistry: Principles of Water Chemistry – Previous Year Questions
18 GATE previous year questions on Principles of Water Chemistry (Environmental Chemistry, Environmental Science and Engineering) with answers and explanations, from every paper.
- GATE 2021 ES Q27 – Water has H⁺ concentration10 mg/L. Hydrogen atomic mass1 g/mol. Find pH.
- GATE 2021 ES Q41 – A 200 mL sample atpH9 requires 25 mL of .02 N H₂SO₄ to reachpH4.5. Find total alkalinity in mg/L as NaHCO₃. Atomic masses Na23,H1,C12,O16,S32,Ca40.
- GATE 2021 ES Q63 – Water containsNa⁺ .25 M, Ca²⁺ .12 M, Cl⁻ .32 M, HCO₃⁻ .05 M. Find ionic strength in M, to two decimals.
- GATE 2021 ES Q64 – Excess solid CaSO₄ is added to pure water atpH7,with undissolved solid remaining. Ksp=2.1×10⁻⁵ mol²/L². Find equilibrium sulfate concentration in…
- GATE 2022 ES Q15 – Specific conductance indirectly estimates dissolved solids in water. Which species contribute to the measurement?
- GATE 2022 ES Q21 – For recarbonation,1 L solution contains 1 mol/L supersaturated calcium carbonate. How many grams CO₂ completely convert it to dissolved calcium ions?
- GATE 2022 ES Q54 – Water at pH6 contains .001 mol/L zinc ions. Zinc hydroxide Ksp=8×10⁻¹⁸ (mol/L)³. Ignore activities. Find reaction quotient/Ksp, to two decimals.
- GATE 2022 ES Q55 – CO₂ Henry constant at 25°C is .034 M/atm in neutral water. CO₂·H₂O⇌H⁺+HCO₃⁻ has K₁=4.3×10⁻⁷ M; HCO₃⁻⇌H⁺+CO₃²⁻ has K₂=4.7×10⁻¹¹ M. Ambient CO₂300 ppm.…
- GATE 2023 ES Q14 – A water sample is colorless with phenolphthalein but yellow after methyl-orange addition. Which alkalinity interpretation is intended?
- GATE 2023 ES Q50 – Gas A has aqueous solubility16 mg/L at vapor pressure.042 atm and 25°C. In a closed system its gas concentration is 10⁻³ mol/L. Use ideal R=.0821…
- GATE 2024 ES Q38 – A saturated CaCO 3 stock solution is at 25°C. Experiment(i) adds25 g Na 2CO 3;experiment(ii) adds25 g Na 2SO 4. Which describes the calcium…
- GATE 2024 ES Q50 – A buffer contains .1 M acetic acid and .05 M sodium acetate. Given pKa4.76,find pH, to two decimals.
- GATE 2024 ES Q51 – Find ionic strength of a solution containing.01 M CaCl 2 and .001 M Na 2SO 4,in M, to three decimals.
- GATE 2024 ES Q54 – Mix2 MLD wastewater at 45°C, pH2 with 3 MLD at 30°C, pH8. Neglect buffering and temperature effects on pH. Find mixed pH, to two decimals.
- GATE 2025 ES Q36 – A researcher adds HgCl 2 to water at pH 10 and calculates expected mercury concentration from the added mass. An instrument measuring only free Hg2+…
- GATE 2025 ES Q37 – Label regions I–IV of the phosphoric-acid speciation diagram.
- GATE 2026 ES Q51 – For SO 2(aq) H++HSO 3- and HSO 3- H++SO 32-,the ideal equilibrium constants are K S1=1.310-2 M and K S2=6.610-8 M. At pH 4.0 and [SO 2(aq)]=1.0 M,…
- GATE 2026 ES Q52 – The figure calibrates absorbance against chromate concentration (CrO 42-,mg/L). For sample absorbance .35,find Cr(VI) concentration in mg/L, to two…