The average atomic mass of chlorine using the following data would be:

Isotope

% Natural

Abundance

Molar Mass

35Cl  75.77 34.9689
37Cl  24.23 36.9659


1. 38.4527 u

2. 37.4527 u

3. 36.4527 u

4. 35.4527 u

Subtopic:  Empirical & Molecular Formula |
 78%
Level 2: 60%+
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Determine the number of moles of hydrogen atoms present in 3 moles of ethane (C2H6):

1. 18.069 × 1023

2. 1.8 × 1023

3. 18

4. 6 × 1023

Subtopic:  Moles, Atoms & Electrons |
 65%
Level 2: 60%+
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20 g of sugar is dissolved in enough water to make a final volume of 2L. The concentration of sugar (C12H22O11) in mol L–1  will be:

1. 0.29 mol/L

2. 0.029 mol/L

3. 0.35 mol/L

4. 0.032 mol/L

Subtopic:  Concentration Based Problem |
 78%
Level 2: 60%+
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How much volume of methanol is needed to prepare 2.5 L of a 0.25 M solution, if the density of methanol is 0.793 kg/L?

1. 22.25 mL
2. 24.78 mL

3. 25.22 mL 

4. 28.52 mL

Subtopic:  Concentration Based Problem |
 62%
Level 2: 60%+
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If the mass of air per unit area at sea level is 1034 g cm–2, pressure in pascal will be:

1. 1.01332 × 105 Pa

2. 1.01332 × 106 Pa

3. 1.01332 × 10Pa

4. 1.01332 × 108 Pa

Subtopic:  Introduction |
 67%
Level 2: 60%+
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The SI unit of mass is:

1. Kilogram (kg)

2. Gram (g)

3. Pascal (Pa)

4. Kilometres (km)

Subtopic:  Introduction |
 88%
Level 1: 80%+
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A significant figure is defined as :

1. The total number of digits in a number, including the last digit that represents the uncertainty of the result. 
2. The total number of digits in a number, excluding the last digit, which represents the uncertainty of the result.
3. The total number of digits in a number including the last digit that represents the certainty of the result. 
4. The total number of last digits that represents the uncertainty of the result. 

Subtopic:  Introduction |
 50%
Level 3: 35%-60%
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The chloroform contamination level in water is 15 ppm (by mass of chloroform). Calculate the molality of chloroform in this water sample, which represents the number of moles of chloroform dissolved per kilogram of pure water solvent:

1. 3.25 × 10-4

2. 1.5 × 10-3

3. 7.5 × 10-3

4. 1.25 × 10-4
Subtopic:  Concentration Based Problem |
 50%
Level 3: 35%-60%
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If the speed of light is 3.0 × 108 m s–1, then the distance covered by light in 2.00 nanoseconds will be -

1. 0.500 m

2. 0.600 m

3. 0.700 m

4. 0.800 m

Subtopic:  Introduction |
 88%
Level 1: 80%+
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In a reaction A + B2 → AB2, 
A will act as a limiting reagent if :

i. 300 atoms of A reacts with 200 molecules of B
ii. 2 moles A reacts with 3 moles B2
iii. 100 atoms of A reacts with 100 molecules of B
iv. 5 moles A reacts with 2.5 moles B
v. 2.5 moles A reacts with 5 moles B2

 
Choose the correct option:

1. (i), (ii) 2. (i), (ii), (v)
3. (ii), (v) 4. All
Subtopic:  Limiting Reagent |
 71%
Level 2: 60%+
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