CBSE
Multiple Choice QuestionsIf Avogadro number NA, changed from 6.022 x 1023 mol-1 this would change
the definition of mass in units of grams
the mass of one mole of carbon
the ratio of chemical species to each other in the balanced equation
the ratio of chemical species to each other in the balanced equation
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
Mole fraction of the solute in a 1.00 molal aqueous solution is
0.0177
0.0344
1.7700
1.7700
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
Equal masses of H2, O2 and methane have been taken in a container of volume V at temperature 270 C in identical conditions. The ratio of the volumes of gases H2 : O2: CH4 would be
8:16:1
16:8:1
16:1:2
16:1:2
1.0 g of magnesium is burnt with 0.56 g of O2 in a closed vessel. Which reactant is left in excess and how much?
Mg, 0.16 g
O2, 0.16 g
Mg, 0.44 g
Mg, 0.44 g
Equal moles of hydrogen and oxygen gases are placed in a container with a pin-hole through which both can escape. What fraction of the oxygen escapes in the time required for one-half of the hydrogen to escape?
1/4
3/8
1/2
1/2
When 22.4 L of H2 (g) is mixed with 11.2 L of Cl2 (g), each of at STP, the moles of HCl (g) formed is equal to
1 mole of HCl (g)
2 moles of HCl (g)
0.5 mole of (g)
0.5 mole of (g)
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
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
