What is the killing of aquatic life due to the depletion of oxygen because of the excessive growth of algae due to the over-abundance of phosphorous in the coastal areas called?

What environmental issue involves the excessive use of fertilizers and run-off chemimls into bodies of water. causing oxygen depletion and harm to aquatic ecosystems?

A

Acid rani

B

Eutrophication

C

Desertification

D

Deforestation

Directions : In each of the following questions a statement is given, followed by two conclusions. Give answer :

Statements : The average number of persons per household is 5 in urban areas whereas it is 7 in rural areas. The national average is 6.

Conclusions :
I. The population per unit area in the rural areas is higher than in the urban areas.
II. More persons live in the same household in the rural areas as compared to those in the urban areas.

A

Only conclusion I follows

B

Only conclusion II follows

C

Either I or II follows

D

Neither I nor II follows

E

Both I and II follow

A diode had a transition capacitance of 1pF and depletion width of 1 µm. The capacitance changes to 10 pF when the depletion width changes. The final depletion width is __________

A

10 µm

B

0.1 µm

C

1 µm

D

100 µm

In a well aerated and agitated microbial culture, the 'supply' of oxygen is equal to 'demand' (uptake) of the growing culture. The K_La for such a system will be (K_La = volumetric mass transfer coefficient, C* = dissolved oxygen concentration in liquid in equilibrium with gaseous oxygen, C = instantaneous value of dissolved oxygen concentration, 'r' = specific oxygen uptake rate per unit weight of cells, X = dry weight of the cells per unit volume)

A

$$\frac{{\left( {rX} \right)}}{{\left( {C* - C} \right)}}$$

B

$$\frac{{\left( r \right)}}{{X\left( {C* - C} \right)}}$$

C

$$\frac{{\left( {C* - C} \right)}}{{\left( {rX} \right)}}$$

D

$$\frac{{\left( X \right)}}{{r\left( {C* - C} \right)}}$$

What is the growth of huge amounts of algae and other aquatic plants leading to the deterioration of the water quality called?

A

Eutrophication

B

Algae growth

C

Nitrification

D

Denitrification

A bacterial culture having a specific oxygen uptake rate of 5 mmol O₂ (g DCW)^-1 hr^-1 is being grown aerobically in a fed-batch bioreactor. The maximum value of the volumetric oxygen transfer coefficient is 0.18 s^-1 for the stirred tank bioreactor and the critical dissolved oxygen concentration is 20% of the saturation concentration (8 mg mL^-1). The maximum density to which the cells can be grown in the fed-batch process without the growth being limited by oxygen transfer, is approximately

A

14 g L^-1

B

26 g L^-1

C

32 g L^-1

D

65 g L^-1

Conversion of yellow phosphorous to red phosphorous is done by heating it in covered retorts at __________ °C in absence of air.

A

50-80

B

250-400

C

1000-1200

D

800-900

The most stable allotropic form of phosphorous is the __________ phosphorous.

A

White

B

Black

C

Yellow

D

Red

Red phosphorous is changed into white phosphorous by

A

Heating in presence of light

B

Melting under pressure

C

Vaporisation followed by condensation

D

None of these

Both white phosphorous as well as red phosphorous

A

Are soluble in CS₂

B

Burns when heated in air

C

Reacts with hot caustic soda solution to give phosphine

D

All of the above

What is the killing of aquatic life due to the depletion of oxygen because of the excessive growth of algae due to the over-abundance of phosphorous in the coastal areas called?

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