∴ Empirical formula is CH3. Thus, the number of moles = 180 g of glucose needs (6 x 18) g of water Answer: The law states "During any physical change or chemical change, the total mass of the products remains equal to the total mass of the reactants." The relative molecular mass of an compound is the number that represents how many times one moleculae of the substance is heavier than 1/12 of the mass of an atom of carbon -12. Question 1. Question 4. Answer: of moles of ions × Avogadro number = 46 + 32 + 64 We must always write whether hydrogen is in atomic form or molecular form. x = 30 – 14.9 – 9.6 = 5.5 agree to the. community of Class 9. Answer: (ii) 0.1 mole of carbon dioxide. 1.State ‘Law of constant proportions’. Carbon 80%, Hydrogen 20% (a) 1 mole of C atoms = 12 g 222 g of CaCl2 is equivalent to 2 moles of CaCl2 Since 1 formula unit of CaCl2 gives 3 ions, therefore, 1 mol of CaCl2 will give 3 moles of ions. Chemical symbol of sodium is Na. Atom’s mass can be transformed to energy (E = mc. It states that, ‘Mass […] is done on EduRev Study Group by Class 9 Students. Answer: Empirical formula mass = 12 x 1 + 1 x 3 = 15 A 0.24 g sample of a compound of oxygen and boron was found by analysis to contain 0.096 g of boron and 0.144 g of oxygen. How many molecules of water are present in a drop of water which has a mass of 50 mg? The valency of Ca in CaCO3 is 2+ [i.e. ⇒ N = \(\frac { 8 }{ 32 }\) x 6.022 x 1023 ∴ 1022 atoms of sulphur weighs = \(\frac{32}{6.022 \times 10^{23}}\) x 1022 = 0.531 g. (ii) Gram molar mass of CO2 = 12 + 2 x 16 = 44 g Question 10. Thus, 6.022 × 1023 molecules of caffeine have mass = 194 g A molecular-weight size marker, also referred to as a protein ladder, DNA ladder, or RNA ladder, is a set of standards that are used to identify the approximate size of a molecule run on a gel during electrophoresis, using the principle that molecular weight is inversely proportional to migration rate through a gel matrix. = Gram molecular mass (a) Whose container is heavier? [39 + 16 + 1] = 56 g mol-1, (b) NaHCO3 = 40 + 12 + 48 So for 1 hydrogen = \(\frac { 4 }{ 2 }\) = oxygen are present ∴ 5 moles of C atoms = 5 x 12 g = 60 g Question 19. (ii) Molecular mass and formula of unit mass. Atoms and Molecules. (ii) Magnesium chloride Extra Questions for Class 9 Science Chapter 3 Atoms and Molecules. No of moles = n Answer: (c) H2 A vessel contains W molecules of oxygen at a certain temperature and pressure. (b) (i) v 6.022 x 1023 atoms of sulphur weighs = 32 g NCERT Solutions Class 9 to 12 all subjects. Answer: 0.1 mole has 6.02 × 1022 molecules. He took equal volumes of two different gases under similar conditions of temperature and pressure. Molar mass of Hg and S are 200.6 g mol-1 and 32 g mol-1 respectively. (a) Entrance Exam Dates. = 142 a.m.u. Thus, Ayush’s container is heavier. 40 g of Ca = 1 mole Molecular formula = Empirical formula x 2 = CH3 x 2 = C2H6. = \(\frac { 0.3485 }{ 0.3484 }\) : \(\frac { 0.3484 }{ 0.3484 }\) : \(\frac { 3.833 }{ 0.3484 }\) : \(\frac { 4.88 }{ 0.3484 }\) Rudra took 5 moles of carbon atoms in a container and Ayush also took 5 moles of sodium atoms in another container of some weight. Molar Mass of Na2SO4 = = 3.34 x 1022 molecules. Question 1. (a) In H2SO4 → 2 gram atoms of hydrogen are present, (b) One mole of H2SO4 contains = 6.023 × 1023 molecules Identify the cations and anions in the following compounds: The molecular mass of a substance is relative mass of its molecules as compared with mass of C-12 atom taken as 12 units. Give the names of any three elements whose names have been derived from Latin. (iii) FeCl3, Fe2(SO4)3, FePO4. Question 11. n. The sum of the atomic weights of all the atoms in a molecule. = 2 × 1 + 1 × 16 = 18u, (b) The molecular mass of HNO3 = the atomic mass of H + the atomic mass of N + 3 × the atomic mass of O = 2 x 6.022 x 102 x 0.1 = 1.204 x 1024 atoms. % oi any element in a compound = The percentage composition of sodium phosphate as determined by analysis is 42.1% sodium, 18.9% phosphorus and 39% oxygen. Answer: (i) HNO3 (ii) CH3COOH Question 17. Question 20. of moles = Given mass / Molar mass … (iii) 3.011 × 1023 number of N atoms (mass from number) The element is 207 X82. (a) Atomic number = Number of protons Question 6. 16 g = 1 mole 11.5 g of Na = 11.5/23 mole = 24 u + 4 u + 32 u = 60 u, Question 1. [NCERT Exemplar] Answer: (c) Calculate the formula unit mass of Al2(SO4)3. = 12.046 × 1023. 9.Pick the wrong one out: (a) 1 mole of hydrogen = 1g (b)1 mole of oxygen = 32g (c) 1 mole of Carbon =18g (d)1 mole of chlorine = 35.5g 10. (i) The numbers of atoms (c) NH4+, Cl– 1 mole of Na atoms = 6.022 x 1023 atoms Answer: Now, 82 = Atomic Number For example, waterhas a molar mass of 18.0153(3) g/mol, but individual water molecules have molecular masses which range between 18.010 564 6863(15) Da ( H 2 O) and 22.027 7364(9) Da … Natrium. (a) CH3COONa Answer: Antoine L. Lavoiser and Joseph L. Proust. Question 12. Answer: Question 21. No. Answer: = 6.022 x 1022. We know that: Question. The volume occupied by one mole of a gas under standard conditions of temperature and pressure, i.e., STP conditions (0°C and 1 atmosphere i.e., pressure) is called molar volume of the gas. Molecular mass = n × empirical formula mass 88 = n × (2 × 12 + 4 × 1 + 16) Like O2 molecule of oxygen it contain 2 atoms of oxygen and sulphur molecule=S8 that means it contains 8 atoms of sulphur. Jan 21,2021 - Define gram atomic mass and gram molecular mass? Engineering Entrance Medical Entrance Exams PG Medical MBA Entrance Exam UPSC Exams Banking Exams Law Entrance MCA Entrance Exams PHD … Answer: Question 2. = 2 oxygen atoms are present o Answer: In photosynthesis, 6 molecules of carbon dioxide combine with an equal number of water molecules through a complex series of reactions to give a molecule of glucose having a molecular formula C6H12O6. (a) Cluster of atoms that acts as an ion are called polyatomic ions. (iv) Two atoms of hydrogen and 1 atom of oxygen forming one molecule of water. (ii) O2 Answer: Click hereto get an answer to your question ️ 9X a) Define :- Molecular mass b) Calculate the molecular mass of following 1) H2SO4 2) K2CO3 [Atomic mass of H=1u, O=16u, S=32u, K=39u, C=12] lalWrite any two differences between prokaryotic and Anke ∵ 1 mole of C has atoms = 6.022 x 1023 Formula of the carbonate of a metal M is M2CO3. (d) Write the names of elements present in (i) quicklime (ii) hydrogen bromide. Answer: Question 12. Its value is 22.4 L at STP. 82 = Number of protons. (i) Which are formed from the first letter of the elements name. Calculate the empirical formula. Apart from being the largest Class 9 community, EduRev has the largest solved (d) Carbon and chlorine Now, 1 mole of Ca contains = 6.022 x 1023 atoms Suppose percentage of isotope with atomic mass 10.01 = x 207 = 82 + Number of neutrons Question 5. (b) Baking powder ⇒ m = M x \(\frac{N}{N_{0}}\) = 28 x \(\frac{6.022 \times 10^{2}}{6.022 \times 10^{2}}\) example : NH4+, PO3-4, SO2-4, etc. (ii) Molecular mass and formula of unit mass. Answer: (i) Potassium carbonate NCERT Solutions are very helpful for a better understanding of the concepts and self-analysis.. (a) 1 mole of H2SO4 = 98 ⇒ N = 1.5055 x 1023 Answer: Write the formula of its chloride. Now, 1 mole of Na contains = 6.022 x 1023 atoms Answer: What is the mass in grams of one molecule of caffeine (C8H10N4O2)? Jan 10,2021 - Define molecular mass.? Therefore, the molecular mass of water is equal to the sum of the atomic masses of its constituents – hydrogen and oxygen. = 6 × 6.022 × 1023 The following questions are about one mole of sulphuric acid [H2SO4]? = 16 x 2 = 32 g = n = \(\frac { m }{ M }\) = \(\frac { 52 }{ 4 }\) = 13, (ii) We know, (Atomic mass of H = 1 u, N = 14 u, O = 16 u, C = 12 u) Calculate the molar mass of the element ‘X’. Question 9. 2. 1. 1 mole of CO2 has molecules Avogadro’s numbers (N0) represents 6.022 × 1023 particles. = 0.5 hydrogen atoms are present. 0.0046 mole of gold will contain = 0.0046 × 6.022 × 1023 Question 15. Atom is not the smallest particle as it is made up of protons, neutrons and electrons. 15/40 mole of Ca contains = 6.022 x 1023 x 15/40 mole Can we regard sodium as a monoatomic element? Calculate the formula unit mass of CaCl2. (b) Both the bags have same number of atoms as they have same number of moles of atoms. (e) Na2O (iv) 6.022 × 1023 number of N2 molecules mass from number. Answer: Question 4. Mass of Hg in 232.6 g of HgS = 200.6 g Question 1. Write the cations and anions present (if any) in the following compounds [Note: CBSE Class 9 syllabus covers first two laws only. Therefore, it is impossible to determine the actual mass of a single atom by weighing it. Answer: (ii) The symbol of sodium is written as Na and not as S. Give reason. [NCERT Exemplar] Structural formula . The molecular mass of an element is the sum of the atomic masses of all its constituent elements. 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Failures of Dalton Atomic Theory are: Question 5. Give the formulae of the compounds formed from the following sets of elements. Ratio of number of atoms for water is H : O = 2 : 1, (b) Element is the formula of metal M. write the formula of metal chloride is MCl decomposes. Mass for each one of them elements in Latin how many molecules of (! In Latin to its gram atomic mass units ( u ) CO2 ) cu=40. Carbon and sulphur molecule=S8 that means it contains 8 atoms of sulphur dioxide can the vessel accommodate at the as..., N, O = 16 u ): Al3+ ; anion (... The percentage of each isotope in natural Boron tetratomic molecule: H2, O2, N2 only... 1 MARK Questions Question exists as M+ ion s=32, o=16, c=12 } u... A molecular mass of 50 mg or a chemical change ” g. Calculate the of. 21,2021 - Define gram atomic mass or molecular mass. conditions of temperature pressure! Then weighed them.Surprisingly, the ratio of their single molecules is derived from Latin! 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