Water samples were collected at points A, B and C in a segment of a river near a sugar factory and tested for BOD level. The BOD levels of samples A, B and C were 400 mg/L, 480 mg/L and 8 mg/L respectively. What is this indicative of? Explain why the BOD level gets reduced considerably at the collection point C?

BOD values of 4 water samples A, B, C, D are 60, 80, 100 and 150 mg/lit respectively. Which is more polluted

Three water samples namely river water, untreated sewage water and secondary effluent discharge from a sewage treatment plant were subjected to BOD test. The samples were labelled A,B and C. but the laboratory attened did not note, which was which . The BOD values of the three samples A,B and C were recorded as 20 mg/L , 8 mg/L and 400 mg/L, respectively. which sample of the water is most polluted ? can you assign the correct label to each , assuming the river water is relatively clean

Four samples of water A, B, C and D have the DO values 1 mg / litre, 3 mg /litre, 5 mg / litre and 8 mg/litre respectively. The more polluted sample of water is

A circle is circumscribed about a right angled triangle ABC right angled at vertex B.Line L is a tangent to this circle drawn at point B. Length of perpendiculars drawn from vertices A and C upon L are 5 and 8 respectively,then radius of the this circumcircle can be

Answer the following : (a) The triple-point of water is a standard fixed point in modern thermometry. Why ? What is wrong in taking the melting point of ice and the boiling point of water as standard fixed points (as was originally done in the Celsius scale) ? (b) There were two fixed points in the original Celsius scale as mentioned above which were assigned the number 0^(@)C" and "100^(@)C respectively. On the absolute scale, one of the fixed points is the triple-point of water, which on the Kelvin absolute scale is assigned the number 273.16 K. What is the other fixed point on this (Kelvin) scale ? (c ) The absolute temperature (Kelvin scale) T is related to the temperature t_(c) on the Celsius scale by t_(c)=T-273.15 Why do we have 273.15 in this relation, and not 273.16 ? (d) What is the temperature of the triple-point of water on an absolute scale whose unit interval size is equal to that of the Fahrenheit scale ?

A stone of mass m is tied to an elastic string of negligble mass and spring constant k. The unstretched length of the string is L and has negligible mass. The other end of the string is fixed to a nail at a point p. Initially the stone is at the same level as the point P. The stone is dropped vertically from point P. (a) Find the distance y from the top when the mass comes to rest for an instant, for the first time. (b) What is the maximum velocity attained by the stone in this drop? (c) What shall be the nature of the motion after the stone has reached its lowest point?