IIT JEE 2006 Sample Question Paper

Passage 4

The following table represents the concentration of ions and dissolved gases in the sediment at the bottom of an ocean. A depth of 0 centimeters (cm) represents the top of the sediment. The concentrations are expressed in parts per million (ppm). The acidity of a solution is represented on a scale known as pH. A pH of 1 is very acidic, a pH of 7 is neutral, and a pH of 14 is very basic.

Depth (cm)	Temperature (oC)	pH	Concentration in sediment (ppm)
			SO42-	S2-	CO2	Fe3+	Fe2+	O2
0	4	7.0	7.0	0.0	1.0	4.0	0.5	2.0
5	5	6.5	5.0	2.0	1.5	3.0	1.5	1.0
10	7	6.0	3.5	3.5	2.0	2.0	2.0	0.0
15	9	5.5	3.3	3.8	3.0	0.8	3.8	0.0
20	10	5.0	3.0	4.0	1.0	0.5	4.0	0.0

Q. 16 According to the information provided in the table, the concentration of which of the following ions and dissolved gases is constant for sediment depths of 10 cm or more?

1. Sulfide (S^2-)
2. Carbon dioxide (CO₂)
3. Ferric iron (Fe³⁺)
4. Oxygen (O₂)

Q. 17 The graph below best represents the relationship between concentration and sediment depth for which of the following ions and dissolved gases?

1. Ferrous iron (Fe²⁺)
2. Oxygen (O₂)
3. Carbon dioxide (CO₂)
4. Sulfate (SO₄^2-)

Q. 18 If the trends indicated in the table were to continue, one would predict the pH of the sediments at a depth of 35 cm to be:

1. 1.5.
2. 3.5.
3. 4.5.
4. 6.0.

Q. 19 A certain type of bottom-dwelling microorganism thrives under the following environmental conditions: low concentrations of Fe²⁺, high concentrations of O₂, and a neutral pH. Based on the table, at which of the following sediment depths would one most likely find this microorganism?

1. 0 cm
2. 5 cm
3. 10 cm
4. 15 cm

Q. 20 A researcher wants to determine whether an unidentified sediment sample was drawn from a depth of 15 cm or 20 cm. Based on the information in the table, which of the following would NOT confirm the depth of the sample?

1. O₂ concentration
2. Fe³⁺ concentration
3. S^2- concentration
4. pH