(b) Gay – Lussacâs law Solution: % of Oxygen $$=\frac{192}{342} \times 100=56.14 \%$$. (ii) 23 g of sodium No. Atomic mass of 1(O) = 1 Ã 16 = 16 We know that one mole of sodium contains 6.022 Ã 1023 atoms. 24 : 71, (c) H2SO4 How many times heavier is one atom of carbon than one atom of oxygen? Number of moles = GMM = 12 Ã 12 + 22 Ã 1 + 11(16) â 10x + 11 – 11x = 10.804 amu Answer: Give an example for each type? (b) 14 amu Answer: Answer: â´ 0.1 g atom of Ag = 0.1 Ã 108 g = 10.8 g Question 16. Question 3. (d) 6 litres of Hydrogen. Atoms of the same element with same atomic number but a different mass number are called _____. (d) 1 g of Fe Number of moles of O2 $$=\frac{\text { Volume at S.T.P }}{\text { Molar volume }}$$ $$=\frac{3}{22.4}$$ = 0.1339 moles Atomic mass of 3(O) = 3 Ã 16 = 48 g Atomic mass of calcium = 40 Ca : O Ã 2 : H Ã 2 Question 1. 0.0028 mole of water contain molecules = 6.022 Ã 1023 Ã 0.0028 = 1.68 Ã 1021Â molecules. Reason (R): Atoms of the same element have the same atomic number but a different mass number. Answer: Answer: On heating the powder, it will char if it is a sugar. Answer: Atomic mass of 4(H) = 4 Ã 1 = 4 g Mass of Ca = 40 g The weight % of Mg as 2.68 Question 6. = 6 Ã 6.022 Ã 1023 â 2 Ã vapour density = Relative molecular mass of a gas. Except for noble gases, atoms of most of the elements are found in the combined form. Solution: 36 g of water = $$\frac{1}{18} \times 36$$ = 2 moles. Question 4. (d) $$\frac { 1 }{ 4 }$$ mole. (a) $$_{17} \mathrm{Cl}^{35},_{17} \mathrm{Cl}^{37}$$ Correct statement: The value of Gram molar volume at STP is 22.4 litres. Give the salient features of âModern atomic theoryâ. Avogadro’s law determines the relation between molecular mass and absolute density. (c) Incorrect, the correct symbol of aluminium is Al. (iii) Molecular formula of the gases can be derived. Answer: }}{\text { Molar volume at } \mathrm{S} . (a) 6.023 Ã 102 N2 molecules The volume occupied by 4.4 g of CO2 at S.T.P is _____. Answer: Answer: (c) 3 (d) both (a) and (b) How many atoms of gold are present in one gram of this sample of gold? 67.2 litre of NH3 = $$\frac{1}{22.4} \times 67.2$$ = 3 moles of NH3. Answer: (iv) 1.4 g of lithium _____ are the building blocks of matter. y = % abundance of B – 11 = 100 – 19.6 = 80.4 % 1 mole of CCl4 = 6.02 2 Ã 1023 molecules of CCl4 (or) Question 29. Same, different. Answer: (c) C – 12 = 0.1764 mol Answer: Since 1 formula unit CaCl2 gives 3 ions, therefore, 1 mole of CaCl2 will give 3 moles of ions. Question 5. Isobars are the atoms of the different elements with the same atomic number and different mass numbers. Oxygen. (i) H2O Answer: 40 = Mass number = Number of protons + Number of neutrons (a) 6.023 Ã 1023 (Avogadro number). Answer: (c) mono atomic, Question 53. Question 14. Question 35. 32. Mass of the substance = $$\frac{\text { Gram molecular mass } \times \text { Number of particles }}{\text { Avogadro number }}$$ (a) 22.4 L The mass number is the sum of the number of protons and neutrons in an atom. 98 g of sulphuric acid = 1 mol Atomic mass of carbon = 12 u (a) 1 g of CO2 (d) Both (A) and (R) are correct. (d) 1.5 Ã 1023 How many grams are there in the following? 40 : 32 : 2 Atomic mass of 1(N) = 1 Ã 14 = 14 II. The atomic mass of sodium is 23. (ii) What is the mass of sodium bicarbonate used in this equation? Flask Q has a greater number of oxygen atoms as compared to the flask P. Question 3. One mole of screw weighs = 2.475 Ã 1024 g = 2.475 Ã 1021 kg 8.0 g of calcium = 1 mol Ã $$\frac{(8.0 \mathrm{g})}{(40 \mathrm{g})}$$ = 0.2 mol. Its value is equal to 22.4 litre or 22400 ml or 22400 cmÂ³ or 2.24 Ã 10-2 mÂ³. Diatomic, monoatomic, Question 5. (d) 1 g of Fe [NCERT Exemplar] 2.5 mole of CO2 at S.T.P. (b) Glucose (C6H12O6), Question 22. (d) 12.046 Ã 1023. Which one of the following is a hetero triatomic molecule? (i) H2O (b) V â n. Question 26. Given: molarity, volume, and molar mass of solute. (b) $$\frac{1}{12^{th}}$$ of the mass of a C – 12 atom An example of a triatomic molecule is _____. How many atoms are present in 5 moles of oxygen? â´ 0.18 g of water contains False. Relative atomic mass of an element is the ratio between the average mass of its isotopes to 1 / 12th part of the mass of a carbon – 12 atom. 1.6 g of methane contain molecule = $$=\frac{6.022 \times 10^{23}}{(16 \mathrm{g})} \times(1.6 \mathrm{g})$$ = 6.022 Ã 1022, (ii) Number of electrons in 6.022 Ã 1022 molecules of methane Number of moles = $$\frac{\text { Mass }}{\text { atomic mass }}=\frac{40}{40}$$ = 1 mole of calcium. Question 1. Calculate the number of moles for a substance containing 3.0115 Ã 1023 molecules in it. (b) 3.011 Ã 1012 Define Mole. Gram molecular mass of 4 moles of P2 Molecular formula of calcium carbonate = CaCO3 (i) It explains Gay-Lussacâs law. Answer: The mass of a proton is equal to: Which one of the two is heavier and by how many times? Molecular mass of CO2 = 12 + 32 = 44 g, (iii) NaOH }}{\text { Mass of } 2 \text { atoms of hydrogen }}\). (d) 6 litres of Hydrogen. Answer: Answer: (a) No. Atomicity of Nitrogen is _____ whereas the atomicity of Helium is _____. (a) 6.023 Ã 1023, Question 5. Number of moles of H2 = $$\frac{6}{22.4}$$ = 0.2678 moles [NCERT Exemplar] â´ 0.0536 g of Mg will have = $$\frac{6.023Ã10^{23}}{24}$$ Ã 0.536 Question 57. Mass Spectrometry. (c) 32 g Question 24. (b) 22.4 litres, Question 25. Give an example to show law of conservation of mass applies to physical changes also. (a) 44 g Answer: (iv) A and R are correct, R doesnât explain A. (i) 2 moles of water Question 18. Aluminium Sulphate – Al2(SO4)3 (b) 2 Number of molecules of CO2 = Number of moles of CO2 Ã Avogadroâs number â´ (a) 1.7 g of NH3 has the highest mass. Calculate the number of moles in each of the following. (c) 0.224 L (iii) NaOH (b) (A) is correct but (R) does not explain (A) Avogadro’s law: Equal volumes of all gases under the same conditions of temperature and pressure contain an equal number of molecules. (b) (A) is correct but (R) is wrong Question 14. Explain with the help of an example. False. (c) Tritium What is its use? (a) 12 g of C – 12 16 g of methane contain molecules = 6.022 Ã 1023 Calculate the number of moles present in: (c) isotones Gram molar mass of sucrose = 342 g. (c) H3 PO4 (Phosphoric acid) (c) $$\mathrm{CO}_{3}^{2-}$$ [NCERT Exemplar] }}{\text { Mass of } 1 \text { atom of hydrogen }}\). where ‘W is the mass of the substance in which number of molecules is to be calculated and âMâ is the molecular mass of the substance. Mass of 1 atom of He = $$\frac{0.004}{6.023 \times 10^{23}}=6.6423 \times 10^{-27} \mathrm{kg}$$. Write the different types of isotopes of oxygen and its percentage abundance. (ii) Tetra-atomic molecules are NH3, PCl3. 3.011 Ã 1023 of ammonia gas molecules? â´ Number of electrons in 6.022 Ã 1022 molecules of CCl4 The average atomic mass of an element becomes fractional due to the presence of ______. Answer: (d) 18 g of CH4. Calculate the ratio between the mass of one atom of hydrogen and mass of one atom of silver. Question 4. Which of the two flasks contains greater number of oxygen atoms? Answer: Thus, 1 g of Li has the largest number of atoms. = 1.2042 Ã 1023 ions, Question 11. Volume occupied by N2 at S.T.P = No. What is meant by percentage composition? (i) 3.011 Ã 1023 number of oxygen atoms. (b) 6.023 Ã 10-23 Answer: Eg: Glucose C6H12O6 C : H : O = 6 : 12 : 6 or 1 : 2 : 1. Assertion (A): $$_{17} \mathrm{Cl}^{35}$$ and $$_{17} \mathrm{Cl}^{37}$$ are isotones. (ii) 2 moles of sulphur molecules, S8 (R) explain (A). 2 : 32 : 64 12 : 3 : 8, (f) Ca(OH)2 (c) Molecular mass of MgSO4 =1 Ã 24 + 1 Ã 32 + 4 Ã 16 (d) 2 moles O2, N2, H2, Cl2, Br2, F2, I2 are hetero diatomic molecules. (iii) (A) is wrong (R) is correct, Question 14. [NCERT Exemplar] (6) N2 (b) C2H5OH Answer: 40 : 16 Ã 2 : 1 Ã 2 (a) isotopes (b) 6.023 Ã 1023 atoms of hydrogen and 6.023 Ã 1023 atoms of oxygen Question 20. 1 mol of water contains 6.022 Ã 1023 atoms of oxygen (d) 2 moles. Answer: Question 11. Calculate the gram molar mass of the following. (c) 98 g, Question 12. $$\begin{array}{l}{\text { (a) } 21 \mathrm{Sc}^{45} \text { and }_{23} \mathrm{V}^{50}} \\ {\text { (b) }_{22} \mathrm{Ti}^{48} \text { and }_{22} \mathrm{Ti}^{50}} \\ {\text { (c) }_{22} \mathrm{Ti}^{50} \text { and }_{23} \mathrm{V}^{50}} \\ {\text { (d) }_{21} \mathrm{Sc}^{45} \text { and }_{22} \mathrm{Ti}^{50}}\end{array}$$ = 0.1345 Ã 1023 atoms of Mg = 1.345 Ã 1022 Hint: (i) H2O % of O = $$\frac{16}{18}$$ Ã 100 = 88.89% Volume occupied by NH3 = number of moles Ã molar volume $$=\frac{44}{6.023 \times 10^{23}} \times 1022=7.466 \times 10^{-20} \mathrm{g}$$. = 4 Ã 124 = 496 g. Question 2. (k) 1 (Noble gases do not combine and exist as monoatomic gases) Correct statement: Isobars are the atoms of the different elements with the same mass number but a different atomic number. Question 8. False. Question 2. H Ã 2 : S : O Ã 4 If it conductsm it is salt. Question 5. Question 1. Answer: â´ 0.056 g of Al2O3 = $$\frac{1 \times 0.056}{102}$$ mol $$\frac{6.023 \times 10^{23}}{32} \times 16=3.011 \times 10^{23}$$, Question 33. â´ Mass of 3.011 Ã 1023 sodium atoms 1 mole of steel screws = 6.022 Ã 1023 screws (c) 1 g of H2 (c) $$\frac { 1 }{ 2 }$$th of the mass of a C – 12 atom H2 (g) + O2 (g) â 2H2O (g) Question 5. A flask P contains 0.5 moles of oxygen gas. Now, Molar mass of H2O = 2(1) + 16 = 18 g 1 mole of Nitroglycerine produces 19 / 4 = 4.75 moles, (iii) Mass of 1 mole of Nitroglycerine C3H5(NO3)3 How many molecules at present in one gram of hydrogen? Answer: 40 g of NaOH = 1 mol (v) Atoms may not always combine in a simple whole number ratio. [Given that atomic mass of Ca = 40 u, Avogadro No. 1 mole of calcium chloride = 111 g Gram molar mass of H2O = 18 g. (ii) CO2 16 g of oxygen will contain $$\mathrm{V.D. (e) Incorrect, the correct symbol of sodium is Na. (l) Ag [NCERT Exemplar] (a) 0.5 mole (a) Both (A) and (R) are correct 2015âpresent Senior Instructor II, University of Oregon. (d) 22400. True or False: (If false give the correct statement). (a) Sulphur, Question 20. Question 10. (ii) H2O2, % of O = \(\frac{32}{34}$$ Ã 100 = 94.12%. (d) C2H6 (b) $$_{18} \mathrm{Ar}^{40},_{20} \mathrm{Ca}^{40}$$ Reason (R): 1 molecule of ozone contains 3 atoms of oxygen. = 1.368 Ã 1022 molecules of CO2. $$\frac{\text { Molecular mass }}{\text { Atomic mass }}$$. Atomic mass of lithium = 7 Question 5. 6.023 Ã 1023 c atoms mass = 12 g $$\frac{2.68}{100}$$ Ã 20 Hint. (d) 16.2 %. Matter. Mass of 0.1 mole of NH3 = 1.7 g. (b) Mass of 1022 atoms of carbon Atomic mass of Au = $$\frac{1}{198} \times 6.023 \times 10^{23}$$ Avogadro’s law. Molar mass of Al3+ = (27 – 0.00164) g mol-1 An aluminium atom needs to lose three electrons to become an ion. Atomic mass of sodium = 23 (a) 22.4 litre (c) 28 g. Question 5. So (d) is correct. Others are less. (d) 0.25. 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