#11th1q4
- A. What is the ratio of molecules in 1 mole of NH3 and 1 mole of HNO3 . Correct answer is 1:1 one mole of any substance,compound , or elements contain particles equal to avagadro's number i.e. 6.022 × 10²³ theref... 1
- B. Calculate number of moles of hydrogen in 0.448 litre of hydrogen gas at STP Given : volume of hydrogen at STP =0.448 L To find : number of moles of hydrogen Formula : number of moles of a gas = Volumespace of space a... 1
- C. The mass of an atom of hydrogen is 1.008 u. What is the mass of 18 atoms of hydrogen. Given : mass of hydrogen = 1.008 u To find : mass of 18 atoms of hydrogen Solution : mass of 18 atoms of hydrogen = 18 × mass of hydrogen =... 1
- D. Calculate the number of atom in each of the following (Given : Atomic mass of I = 127 u). Given : atomic mass of I=127 u A. 254 u of iodine (I) Formula : number of atoms = given space atomic space mass space of space elementover a... 1
- E. A student used a carbon pencil to write his homework. The mass of this was found to be 5 mg. With the help of this calculate. Given : mass of carbon = 5mg = 5× 10⁻³ g Atomic mass of carbon=12u Solution :: a. The number of moles of carbon in his homework writing numb... 1
- F. Arjun purchased 250 g of glucose (C6 H12O6 ) for Rs 40. Find the cost of glucose per mole Given : cost for 250 g glucose = Rs 40 , formula of glucose = C₆H₁₂O₆ To find : cost of glucose per mole solution: molecular formula of gluc... 1
- G. The natural isotopic abundance of 10B is 19.60% and 11B is 80.40 %. The exact isotopic masses are 10.13 and 11.009 respectively. Answer: Average atomic mass of boron = 10.81 u Given: ¹⁰ B: abundance 19.60 %, isotopic mass 10.013 u (given as 10.13 in the question, a pri... 2
- H. Convert the following degree Celsius temperature to degree Fahrenheit. a. 40°C b. 30° C To find : temperature in degree fahrenheit Formula : °F= 9over5(°C)+32 Solution : A. 40°C °F=9over5(°C)+32 =9over5(40)+32 =72+32=104°F B. 30... 1
- I. Calculate the number of moles and molecules of acetic acid present in 22 g of it. To find : the number of moles and molecules present in 22 g of acetic acid Solution : molecular mass of CH₃COOH =(2×atomic mass of C)+(4× at... 1
- J. 24 g of carbon reacts with some oxygen to make 88 grams of carbon dioxide. Find out how much oxygen must have been used. Given :: mass of Carbon = 24 g , mass of carbon dioxide =88g Find : mass of oxygen Solution :: beginmatrix C & +space O₂ & → CO₂\\ 24g & ? &... 1
- L. 2.0 g of a metal burnt in oxygen gave 3.2 g of its oxide. 1.42 g of the same metal heated in steam In first reaction : 3.2 g of metal oxide contains 2g metal therefore % of metal in metal oxide is 2over 3.2× 100=62.5 % and % of oxygen in m... 1
- M.In two moles of acetaldehyde (CH3 CHO) calculate the following a. Number of moles of carbon b. Number of moles of hydrogen Answer: (a) 4 mol C, (b) 8 mol H, (c) 2 mol O, (d) 1.2044 × 10²⁴ molecules Molecular formula of acetaldehyde: CH₃CHO = C₂H₄O. One molecule (... 1
- N. Calculate the number of moles of magnesium oxide, MgO in i. 80 g and ii. 10 g of the compound. Molar mass of MgO= (atomic mass of Mg)+(atomic mass of O) =24+16 =40 g/mol 1) 80g of MgO number of mol = Given space mass over Molar space m... 1
- O. What is volume of carbon dioxide, CO2 occupying by i. 5 moles and i. 5 moles of CO_(2 )gas measured at STP. Solution :: molar volume of gas at STP is 22.4 dm³ mol⁻¹ (n)Number of moles of gas = Volumespace o... 1
- P. Calculate the mass of potassium chlorate required to liberate 6.72 dm3 of oxygen at STP beginmatrix 2KClO₃ &→ 2KCl&+3O₂\\ 2moles & & 3 moles endmatrix 2 moles of KClO₃ = 2× 122.5=245g 3 moles of O₂ =3× 22.4=67.2 dm³ hence , 245... 1
- Q. Calculate the number of atoms of hydrogen present in 5.6 g of urea, (NH2 )2 CO Answer: H = 2.248 × 10²³ atoms; N = 1.124 × 10²³ atoms; C = 5.62 × 10²² atoms; O = 5.62 × 10²² atoms Step 1: Molar mass of urea, (NH₂)₂CO =... 1
- R. Calculate the mass of sulfur dioxide produced by burning 16 g of sulfur in excess of oxygen in contact process. Answer: Mass of SO₂ produced = 32 g Balanced equation: S + O₂ → SO₂ Molar mass of S = 32 g mol⁻¹; molar mass of SO₂ = 32 + 2(16) = 64 g mol⁻... 1