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 :
A. F$^-$ (Fluoride): The allowed concentration is less than 1.5 ppm, but for safe drinking water, it is set at $<$ 50 ppm.
B. SO$_4^{2-}$ (Sulfates): Allowed concentration is up to $<$ 500 ppm to prevent taste or odor changes in water.
C. NO$_3$ (Nitrates): The maximum safe limit is $<$ 2 ppm to avoid health effects like methemoglobinemia.
D. Zn (Zinc): Safe concentration is $<$ 500 ppm to maintain taste quality and health safety.
Thus, the correct matching is A-I, B-II, C-III, D-IV.
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.]
If \[ \frac{dy}{dx} + 2y \sec^2 x = 2 \sec^2 x + 3 \tan x \cdot \sec^2 x \] and
and \( f(0) = \frac{5}{4} \), then the value of \[ 12 \left( y \left( \frac{\pi}{4} \right) - \frac{1}{e^2} \right) \] equals to: