FAQs on International System of Units & Significant Figures Video Lecture - Chemistry Class 11 - NEET
|1. What is the International System of Units (SI)?
Ans. The International System of Units (SI) is a globally recognized system of measurement that is used in scientific research, industry, and everyday life. It provides a standard set of units for measuring physical quantities such as length, mass, time, temperature, and many others. The SI system is based on seven base units, including the meter, kilogram, second, ampere, kelvin, mole, and candela, which are used to derive all other units of measurement.
|2. How does the International System of Units ensure uniformity in measurements?
Ans. The International System of Units (SI) ensures uniformity in measurements by providing standardized units that are universally accepted and used across different countries and disciplines. The SI units are defined based on fundamental constants of nature and are independent of any specific object or substance. This allows for consistency and reproducibility in measurements, promoting accurate and reliable scientific research and international collaboration.
|3. What are significant figures and why are they important in measurement?
Ans. Significant figures are the digits in a number that carry meaningful information about its precision or accuracy. They include all the certain digits plus one uncertain or estimated digit. Significant figures are important in measurement because they indicate the level of precision of a measured value. They help to convey the reliability and limitations of a measurement, especially when performing calculations or comparing measurements. Properly identifying and using significant figures ensures that the results of calculations or experiments are reported with appropriate precision.
|4. How do you determine the number of significant figures in a measurement?
Ans. To determine the number of significant figures in a measurement, follow these rules:
1. Non-zero digits are always significant. For example, in the number 345.2, there are four significant figures.
2. Zeros between non-zero digits are significant. For example, in the number 506, there are three significant figures.
3. Leading zeros (zeros to the left of the first non-zero digit) are not significant. For example, in the number 0.0024, there are two significant figures.
4. Trailing zeros (zeros to the right of the last non-zero digit) are significant if there is a decimal point present. For example, in the number 450.00, there are five significant figures.
5. Trailing zeros without a decimal point are not significant. For example, in the number 1000, there is one significant figure.
|5. How can significant figures be used in calculations?
Ans. When performing calculations with measurements, it is important to maintain the appropriate number of significant figures in the final result to reflect the precision of the original measurements. The rules for significant figures in calculations are as follows:
1. Addition and subtraction: The result should have the same number of decimal places as the measurement with the fewest decimal places.
2. Multiplication and division: The result should have the same number of significant figures as the measurement with the fewest significant figures.
3. Combined operations: Perform the calculations step by step, rounding the intermediate results to the appropriate number of significant figures, before applying the rules above to obtain the final result.