# The total number of valence electrons in 4.2g of ${\mathrm{N}}_{3}^{-}$ ion is (NA is the Avogadro's number) 1. 2.1NA  2. 4.2NA  3. 1.6NA  4. 3.2NA

Subtopic:  Moles, Atoms & Electrons |
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When 22.4L of H2(g) is mixed with 11.2L of Cl2(g) each at STP, the moles of HCl(g) formed is equal to

1. 1 mole of HCl(g)

2. 2 moles of HCl(g)

3. 0.5 mole of HCl(g)

4. 1.5 moles of  HCl(g)

Subtopic:  Moles, Atoms & Electrons |
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The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (at. mass of Al = 27)

1. 180 kg

2. 270 kg

3. 540 kg

4. 90 kg

Subtopic:  Equation Based Problem |
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In the Haber process, 30 L of dihydrogen and 30 L of dinitrogen were taken for the reaction, which yielded only 50% of the expected product. The composition of the gaseous mixture under the said conditions at the end is:

1. 20 L ammonia, 10 L nitrogen, 30 L hydrogen

2. 20 L ammonia, 25 L nitrogen, 15 L hydrogen

3. 20 L ammonia, 20 L nitrogen, 20 L hydrogen

4. 10 L ammonia, 25 L nitrogen, 15 L hydrogen

Subtopic:  Limiting Reagent |
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What is the approximate number of atoms present in 4.25 grams of NH3?

1. 4 x 1023

2. 2 x 1023

3. 1 x 1023

4. 6 x 1023

Subtopic:  Moles, Atoms & Electrons |
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In the reaction, 4NH3(g)+ 5O2(g) $\to$4NO(g) +6H2O(l)

When 1 mole of ammonia and 1 mole of O2  reacts to completion, then:

 1 1.0 mole of H2O is produced. 2 1.0 mole of NO will be produced. 3 All the oxygen will be consumed. 4 All the ammonia will be consumed.

Subtopic:  Equation Based Problem |
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An element X has the following isotopic composition,

200X : 90%, 199X : 8.0%, 202X : 2.0%

The weighted average atomic mass of the naturally occurring element X is closest to:

 1 205 u 2 220 u 3 196 u 4 200 u
Subtopic:  Moles, Atoms & Electrons |
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0.24g of a volatile gas, upon vaporisation, gives 45 mL vapour at NTP. What will be the vapour density of the substance?

(Density of H2 = 0.089)

1. 95.93

2. 59.93

3. 95.39

4. 5.993

Subtopic:  Moles, Atoms & Electrons |
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The hydrated salt, Na2SO4.nH2O, undergoes a 55% loss in mass on heating and becomes anhydrous. The value of n will be:

 1 5 2 3 3 7 4 10
Subtopic:  Empirical & Molecular Formula |
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12 g of Mg (atomic mass = 24) will react completely with an acid to yield:

1. One mole of H

2. A half mole of H2

3. One mole of O2

4. None of the above

Subtopic:  Equation Based Problem |
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