Which one of the following statements is not true?

• Concentration of DO below 6 ppm is good for the growth of fish

• Clean water would have a BOD value of less than 5 ppm

• Oxides of sulphur, nitrogen and carbon are the most widespread air pollutant

• Oxides of sulphur, nitrogen and carbon are the most widespread air pollutant

Mole fraction of the solute in a 1.00 molal aqueous solution is 

• 0.0177

• 0.0344

• 1.7700

• 1.7700

6.02 x 10²⁰ molecules of urea are present in 100 mL of its solution. The concentration of solution is

• 0.02 M

• 0.01 M

• 0.001 M

• 0.001 M

How many grams of the concentrated nitric solution should be used to prepare 250 mL o 2.0M HNO₃ ? The concentrated acid is 70% HNO₃.

• 45.0 g conc. HNO₃

• 90.0 g conc. HNO₃

• 70.0 g conc. HNO₃

• 70.0 g conc. HNO₃

In the Kjeldahl's method for estimation of nitrogen present in a soil sample, ammonia evolved from 0.75 g of sample neutralised 10 mL of 1 M H₂SO₄.The percentage of nitrogen in the soil is

• 37.33

• 45.33

• 35.33

• 35.33