113.  Pick up the correct statement from the following :
A. pH value indicates acidity and alkalinity of sewage
B. In acidic sewage, the pH value is less than 7
C. In alkaline sewage, the pH value is more than 7
D. All the above.

---

114.  The pH value of sewage is determined with the help of
A. Imhoff Cone
B. turbidimeter
C. potentiometer
D. none of these.

---

115.  In sewage having fully oxidised organic matter, the nitrogen exists in the form of
A. nitrites
B. nitrates
C. free ammonia
D. aluminoid nitrogen

---

116.  In very first stage of decomposition of the organic matter in sewage
A. nitrites are formed
B. nitrates are formed
C. carbondioxide is formed
D. ammonia is formed.

---

117.  The presence of free ammonia in sewage, is detected by
A.( a) boiling
B. adding pottassium permanganate
C. adding sulphuric acid
D. phenol-di-sulphuric acid.

---

118.  For detecting the nitrites in the sewage, the matching colour may be developed by adding
A. Pottassium permanganate
B. Sulphuric acid and napthamine
C. Phenol-di-sulphuric acid pottassium hydroxide
D. None of these.

---

119.  For detecting the nitrates in sewage, the colour may be developed by adding
A. Pottassium permanganate
B. Sulphuric acid and napthamine
C. Phenol-di-sulphuric acid and pottassium hydroxide
D. None of these.

---