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Fundamentals of Environmental Chemistry(3)Principles of Water Chemistry(10)Atmospheric Chemistry(1)

Fundamentals of Environmental Chemistry

3 Questions

GATE→2026→Environmental Chemistry→Fundamentals of Environmental Chemistry

Q1

MCQ[1 Mark]

In the reversible reaction shown below, $k_f$ is the forward reaction rate constant and $k_r$ is the reverse reaction rate constant. $A + B \rightleftharpoons C + D$ The CORRECT expression representing the reaction equilibrium constant is

(A)

$k_f + k_r$

(B)

$k_f \times k_r$

(C)

\frac{k_f}{k_r}

(D)

\frac{k_r}{k_f}

Explanation

GATE→2024→Environmental Chemistry→Fundamentals of Environmental Chemistry

Q2

MCQ[1 Mark]

The maximum coordination number of $Sn^{4+}$ is

(A)

4

(B)

8

(C)

6

(D)

2

Explanation

GATE→2022→Environmental Chemistry→Fundamentals of Environmental Chemistry

Q3

MSQ[1 Mark]

If G represents Gibbs free energy, select the correct statement(s):

(A)

If $\Delta G = 0$, reaction will proceed only in one direction

(B)

If $\Delta G = 0$, reaction will be in equilibrium

(C)

If $\Delta G < 0$, reaction will proceed forward

(D)

If $\Delta G > 0$, reaction will not proceed forward

Explanation

Principles of Water Chemistry

10 Questions

GATE→2026→Environmental Chemistry→Principles of Water Chemistry

Q4

NAT[2 Marks]

The following two reactions describe the chemistry of S(IV) in an aquatic system. (i) $SO_{2(aq)} \rightleftharpoons H^+ + HSO_3^-$ ($K_{S1} = 1.3 \times 10^{-2}\text{ M}$) (ii) $HSO_3^- \rightleftharpoons H^+ + SO_3^{2-}$ ($K_{S2} = 6.6 \times 10^{-8}\text{ M}$) If the $\text{pH}$ of the system is $4.0$ and the equilibrium concentration of $SO_{2(aq)}$ is $1.0\text{ M}$, the equilibrium concentration of $SO_3^{2-}$ is _____ mM (rounded off to one decimal place).

Explanation

GATE→2024→Environmental Chemistry→Principles of Water Chemistry

Q5

MCQ[1 Mark]

Hardness in water is NOT caused by

(A)

$Ca^{2+}$

(B)

$Si^{2+}$

(C)

$Mg^{2+}$

(D)

$CO_3^{2-}$

Explanation

GATE→2024→Environmental Chemistry→Principles of Water Chemistry

Q6

MCQ[2 Marks]

A saturated stock solution is existing at $25^\circ\text{C}$. In one experiment (i) $25\text{ g } Na_2CO_3$ is added to the stock solution. In another experiment (ii) $25\text{ g } Na_2SO_4$ is added to the stock solution. Select the correct statement from the following.

(A)

Addition of (i) increases concentration of $Ca^{2+}$ and addition of (ii) decreases concentration of $Ca^{2+}$

(B)

Addition of (i) decreases concentration of $Ca^{2+}$ and addition of (ii) increases concentration of $Ca^{2+}$

(C)

Addition of (i) and (ii) increase the concentration of $Ca^{2+}$

(D)

Addition of (i) and (ii) decrease the concentration of $Ca^{2+}$

Explanation

GATE→2024→Environmental Chemistry→Principles of Water Chemistry

Q7

NAT[2 Marks]

The pH of a solution containing $0.1\text{ M}$ of acetic acid and $0.05\text{ M}$ of sodium acetate is _____ (rounded off to 2 decimal places). The $pK_a$ value of ionization of acetic acid is $4.76$.

Explanation

GATE→2024→Environmental Chemistry→Principles of Water Chemistry

Q8

NAT[2 Marks]

The ionic strength of a solution containing $0.01\text{ M}$ of $CaCl_2$ and $0.001\text{ M}$ of $Na_2SO_4$ is _____ M (rounded off to 3 decimal places).

Explanation

GATE→2023→Environmental Chemistry→Principles of Water Chemistry

Q9

MCQ[2 Marks]

Read the following statements regarding chromium: I. Trivalent chromium has relatively low aqueous solubility, and low mobility in the soil environment. By contrast, hexavalent chromium has a higher aqueous solubility and greater mobility in the soil environment. II. The chemical reaction between trivalent chromium and zero-valent iron will result in transformed version called hexavalent chromium. III. Hexavalent chromium is a known carcinogen. IV. Trivalent chromium has relatively higher human toxicity as compared to hexavalent chromium. The correct choice is

(A)

IV is correct; I and III are incorrect

(B)

II is correct; I and IV are incorrect

(C)

I and III are correct; II and IV are incorrect

(D)

I, II and IV are correct; III is incorrect

Explanation

GATE→2023→Environmental Chemistry→Principles of Water Chemistry

Q10

NAT[2 Marks]

The solubility of gas A is $16\text{ mg/L}$ in water and its vapor pressure is $0.042\text{ atm}$ at $25^\circ\text{C}$. In a closed system, the gas phase concentration of A is $10^{-3}\text{ mol/L}$. Assuming Ideal gas constant ($R$) value as $0.0821\text{ L-atm/mol-K}$, the concentration of gas A in water at $25^\circ\text{C}$ is _____ (in mg/L, rounded off to two decimal places).

Explanation

GATE→2022→Environmental Chemistry→Principles of Water Chemistry

Q11

MCQ[1 Mark]

Carbon dioxide is used in recarbonation process. A solution has $1\text{ mole/L}$ supersaturated calcium carbonate. Estimated amount of carbon dioxide (in grams) needed to completely convert calcium carbonate to calcium ions in $1\text{ litre}$ solution is

(A)

44.000 gram

(B)

0.044 gram

(C)

40.000 gram

(D)

0.040 gram

Explanation

GATE→2022→Environmental Chemistry→Principles of Water Chemistry

Q12

NAT[2 Marks]

A solution has $0.001\text{ mole/L}$ zinc ions having pH of $6$. Solubility product of zinc hydroxide is given as $8 \times 10^{-18}\text{ (mole/L)}^3$. Ignoring activity corrections, the ratio (rounded off to two decimal places) of reaction coefficient to solubility product would be

Explanation

GATE→2022→Environmental Chemistry→Principles of Water Chemistry

Q13

NAT[2 Marks]

The Henry's law constant of $CO_2$ is $3.4 \times 10^{-2}\text{ M per atm}$ in neutral water at $25^\circ\text{C}$. The dissolved $CO_2$ ($CO_2 \cdot H_2O$) at equilibrium undergoes the following reactions: $CO_2 \cdot H_2O \rightleftharpoons H^+ + HCO_3^-$ ($K_1 = 4.3 \times 10^{-7}\text{ M}$) $HCO_3^- \rightleftharpoons H^+ + CO_3^{2-}$ ($K_2 = 4.7 \times 10^{-11}\text{ M}$) If ambient $CO_2$ concentration is $300\text{ ppm}$, the total dissolved $CO_2$ (in $\mu\text{M}$, rounded off to one decimal place) is

Explanation

Atmospheric Chemistry

1 Question

GATE→2026→Environmental Chemistry→Atmospheric Chemistry

Q14

MSQ[1 Mark]

Which of the following chemical reactions is/are related to smog formation in the troposphere?

(A)

$CFCl_3 + h\nu \rightarrow CFCl_2 + Cl\cdot$

(B)

$CH_3O_2 + NO + O_2 \rightarrow HCHO + HO_2 + NO_2$

(C)

$NO_2 + O_2 + h\nu \rightarrow O_3 + NO$

(D)

$CH_4 + 8O_2 \rightarrow CO + H_2O + 2OH\cdot + 4O_3$

Explanation