.

Sewage contains several dissolved and

suspended impurities which pollute the water and

leads to

.

Sewage contains several dissolved and

suspended impurities which pollute the water and

leads to various changes. These are

(i) Water becomes green

(ii) Eutrophication

(iii) Underwater plants die

(iv) Light cannot penetrate the water

(v) Depletion of dissolved oxygen

(vi) Death of aquatic organisms

(vii) Aerobic bacteria feed on dead plants In

which order these changes take place?

(1) (i) o (ii) o (iv) o(iii) o (vii) o (v) o(vi)

(2) (ii) o (i) o (iv) o (vi) o (v) o (iii) o(vii)

(3) (i) o (ii) o (iv) o (iii) o (vii) o (vi)o (v)

(4) (ii) o (i) o (iv) o (iii) o (vii) o(v) o (vi)

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