Q. No.If Avogadro number \(N_{A}\), is changed from \(6 . 022 \times \left(10\right)^{23}\)\(\text{mol}^{- 1}\) to \(6 . 022 \times \left(10\right)^{20} ~\text{mol}^{- 1}\) this would change the:
1.
definition of mass in units of grams.
2.
mass of one mole of carbon.
3.
coefficient of chemical species in a balanced equation.
4.
ratio of elements in a compound.
20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g of magnesium oxide.
The percentage purity of magnesium carbonate in the sample is:
(Atomic weight of Mg=24)
| 1. | 75 | 2. | 96 |
| 3. | 60 | 4. | 84 |
What is the mass of the precipitate formed when 50 mL of 16.9% solution of AgNO3 is mixed with 50 mL of 5.8% NaCl solution? (Ag = 107.8, N = 14, O = 16, Na= 23, Cl = 35.5)
1. 28 g
2. 3.5 g
3. 7 g
4. 14 g
Calculate the mole fraction of the solute in a 1.00 m aqueous solution.
| 1. | 0.177 | 2. | 0.771 |
| 3. | 0.0534 | 4. | 0.0177 |
1. 18 molecules of water
2. 1.8 g of water
3. 18 g of water
4. 18 moles of water
A mixture of gases contains H2 and O2 gases in the ratio of 1 : 4 (w/w). The molar ratio of the two gases in the mixture will be:
| 1. | 1:4 | 2. | 4:1 |
| 3. | 16:1 | 4. | 2:1 |
When 22.4 litres of H2(g) is mixed with 11.2 litres of Cl2(g), both at STP, the moles of HCl(g) formed is equal to:
1. 1 mol of HCl(g)
2. 2 mol of HCl(g)
3. 0.5 mol of HCl(g)
4. 1.5 mol of HCl(g)
1.0 g of magnesium is burnt with 0.56 g O2 in a closed vessel. Which reactant is left in excess and by how much? (At. wt. Mg = 24; O = 16)
| 1. | Mg, 0.16 g | 2. | , 0.16 g |
| 3. | Mg, 0.44 g | 4. | , 0.28 g |
2. 70.0 g conc. HNO3
3. 54.0 g conc. HNO3
4. 45.0 g conc. HNO3
1. 0.01 M
2. 0.001 M
3. 0.1 M
4. 0.02 M
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