# The SI unit of mass is: 1. Kilogram (kg) 2. Gram (g) 3. Pascal (Pa) 4. Kilometres (km)

Subtopic:  Introduction |
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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.

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The chloroform contamination level in water is 15 ppm (by mass of chloroform). The molality of chloroform in the water sample would be:

1. 3.25 × 10-4

2. 1.5 × 10-3

3.  7.5 × 10-3

4. 1.25 × 10-4

Subtopic:  Concentration Based Problem |
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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

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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 |
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If 10 volumes of H2 gas react with 5 volumes of O2 gas, the volumes of water vapor produced would be:

1. 9

2. 8

3. 10

4. 11

Subtopic:  Equation Based Problem |
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15.15 pm in the basic unit will be

1. 1.515 × 1012 m

2. 2.57 × 1011 m

3. 2.87 × 1011 m

4. 1.515 × 10–11 m

Subtopic:  Introduction |
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The number of significant figures present in the answer of the following calculations [(i), (ii), (iii)]  are respectively -

 1 0 . 02856   ×   298 . 15   × 0 . 112 / 5785 2 5 × 5.364 3 0.0125 + 0.7864 + 0.0215

 1 4, 4, 3 2 3, 3, 4 3 4, 3, 4 4 3, 4, 4

Subtopic:  Introduction |
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The molar mass of naturally occurring Argon isotopes is:

 Isotope Isotopic molar mass Abundance 36-Ar 35.96755 g mol–1 0.337% 38-Ar 37.96272 g mol–1 0.063% 40-Ar 39.9624 g mol–1 99.600%

 1 49.99947 g mol-1 2 39.99947 g mol-1 3 35.59947 g mol-1 4 45.59947 g mol-1
Subtopic:  Empirical & Molecular Formula |
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The mass of CaCO3 required to react completely with 25 mL of 0.75 M HCl according to the given reaction would be:

CaCO3(s) + HCl(aq) ➡ CaCl2(aq) + CO2(g) + H2O(l)

1. 0.36 g

2. 0.09 g

3. 0.96 g

4. 0.66 g

Subtopic:  Concentration Based Problem | Equation Based Problem |
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