Why is there a concern about copper smelting plants? 1. They may release lethal quantities of carbon monoxide into environment. 2. The copper slag can cause the leaching of some heavy metals into environment. 3. They may release sulphur dioxide as a pollutant. Select the correct answer using the code given below.

IAS 2021 — Environment & Ecology Environment & Ecology

2021mcqmedium

Why is there a concern about copper smelting plants?

They may release lethal quantities of carbon monoxide into environment.
The copper slag can cause the leaching of some heavy metals into environment.
They may release sulphur dioxide as a pollutant.

Select the correct answer using the code given below.

Official previous-year question

Verified 2 Aug 2026.

Options

A1 and 2 only
B2 and 3 only
C1 and 3 only
D1, 2 and 3

Did you get this right?

Solution

Correct Option (B):

Statement 2 is correct. Copper slag is a significant waste by-product generated during the smelting process. This slag often contains various heavy metals such as arsenic, lead, cadmium, and zinc. Environmental concerns arise because these heavy metals can leach into the surrounding soil and groundwater, particularly through rainwater runoff from slag heaps, leading to contamination.

Statement 3 is correct. The primary method for extracting copper involves smelting sulfide ores (e.g., chalcopyrite, CuFeS₂). During the roasting stage of smelting, sulfide minerals react with oxygen, leading to the release of large quantities of sulfur dioxide (SO₂). Sulfur dioxide is a major air pollutant, contributing to acid rain, respiratory issues, and damage to vegetation and ecosystems.

Incorrect Options:

Statement 1 is incorrect. Copper smelting primarily involves the roasting of sulfide ores and subsequent refining processes. While incomplete combustion can produce carbon monoxide (CO), it is not typically considered a major or lethal pollutant released in significant quantities from standard copper smelting operations compared to sulfur dioxide or heavy metal emissions. Environmental literature emphasizes SO₂ and heavy metal residues as the primary concerns.

Option (A) 1 and 2 only: This option is incorrect because Statement 1 is not a primary environmental concern associated with copper smelting plants.

Option (C) 1 and 3 only: This option is incorrect because Statement 1 is not a primary environmental concern associated with copper smelting plants.

Option (D) 1, 2 and 3: This option is incorrect due to the inclusion of Statement 1, which is not a major concern in copper smelting.

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Correct Option (B):

Incorrect Options:

Option (A) 1 and 2 only: This option is incorrect because Statement 1 is not a primary environmental concern associated with copper smelting plants.

Option (C) 1 and 3 only: This option is incorrect because Statement 1 is not a primary environmental concern associated with copper smelting plants.

Option (D) 1, 2 and 3: This option is incorrect due to the inclusion of Statement 1, which is not a major concern in copper smelting.