Chemistry Class 11 NCERT Solutions: Chapter 1 Some Basic Concepts of Chemistry Part 7

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Q: 20. Round up the following upto three significant figures:

(i)

(ii)

(iii)

(iv)

Answer:

(i)

(ii)

(iii)

(iv)

Q: 21. The following data are obtained when dinitrogen and Dioxygen react together to form different compounds:

This structure is compounds of nitrogen and oxygen

Structure of Dinitrogen and Dioxygen

This structure is compounds of nitrogen and oxygen

Mass of dinitrogen Mass of Dioxygen

(i)

(i)

(iii)

(iv)

(a) Which law of chemical combination is obeyed by the above experimental data? Give its statement.

(b) Fill in the blanks in the following conversions:

(i) 1km = …………………………. mm = ………………………………pm

(ii) 1mg = …………………………. kg = …………………………………ng

(iii) 1mL = ………………………….L = ………………………………….

Answer:

(a) In we fix the mass of dinitrogen at , and then the masses of Dioxygen that will combine with the mass of dinitrogen are the masses of Dioxygen bear a whole number ratio of Hence, the given experimental data obeys the law of multiple proportions. The law states that if two elements combine to form more than one compound, then the masses of one element that combines with the fixed mass of another element are in the ratio of small whole numbers.

(b)

(i)

Hence,

(ii)

(iii)