Q. No.
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. |
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
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
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
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
15.15 pm in the basic unit will be
1. 1.515 × 10–12 m
2. 2.57 × 10–11 m
3. 2.87 × 10–11 m
4. 1.515 × 10–11 m
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 |
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 |
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
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