| List-I (Species) | List-II (Maximum allowed concentration in ppm in drinking water) | ||
| A | F- | I | < 50 ppm |
| B | \(SO^{2-}_4\) | II | < 5 ppm |
| C | \(NO^-_3\) | III | < 2 ppm |
| D | Zn | IV | < 500 ppm |
Choose the correct answer from the options given below :
Solute A associates in water. When 0.7 g of solute A is dissolved in 42.0 gof water, it depresses the freezing point by 0.2°C. The percentage association of solute A in water is :
[Given : Molar mass of A = 93 g mol–1. Molal depression constant of water is 1.86 K kg mol–1.]
A sphere of radius R is cut from a larger solid sphere of radius 2R as shown in the figure. The ratio of the moment of inertia of the smaller sphere to that of the rest part of the sphere about the Y-axis is : 
A constant voltage of 50 V is maintained between the points A and B of the circuit shown in the figure. The current through the branch CD of the circuit is :
The current passing through the battery in the given circuit, is: 
Given below are two statements:
Statement I: The primary source of energy in an ecosystem is solar energy.
Statement II: The rate of production of organic matter during photosynthesis in an ecosystem is called net primary productivity (NPP).
In light of the above statements, choose the most appropriate answer from the options given below:
Heavy water (2H2O, D2O - deuterium oxide) is a form of water that consists only of deuterium rather than the common hydrogen-1 isotope that composes most of the hydrogen in normal water. The presence of the heavier hydrogen isotope gives the water distinct nuclear properties, and the increase of mass gives it slightly distinct physical and chemical properties when compared to normal water.