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Digestive System Disorders: Causes, Symptoms, Treatment & Prevention Guide

Disorders of the Digestive System - Causes, Symptoms & Treatment Disorders of the Digestive System: Causes, Symptoms, Treatment & Prevention 1. Introduction to Digestive Disorders The digestive system breaks down food and absorbs nutrients. Disorders like acid reflux, IBS, or ulcers can interfere with these processes. Understanding symptoms, causes, and treatments is essential for maintaining gut health. 2. Common Digestive System Disorders Acid Reflux (GERD): Stomach acid flows into the esophagus causing heartburn. Peptic Ulcers: Open sores in the stomach or small intestine. Irritable Bowel Syndrome (IBS): Affects bowel habits with cramping and bloating. Constipation: Infrequent or painful bowel movements. Diarrhea: Loose, frequent stools. Inflammatory Bowel Disease (IBD): Includes Crohn's disease and ulcerative colitis. Gallstones: Block bile flow, causing pain an...
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Class 9 Chemistry Chapter 4 Exercise Solutions: stoichiometry


Exercise

1. Tick (√) the correct answer.

(i) How many atoms are there in 1 gram of calcium?

  • (a) 1.505 x 10²² atoms (This is the correct answer)

  • (b) 6.022 x 10²³ atoms

  • (c) 12.044 x 10²³ atoms

  • (d) 1.000 x 10²⁴ atoms

Explanation:

  1. Find the molar mass of calcium (Ca): ~40 g/mol

  2. Calculate moles in 1 gram: 1 g / 40 g/mol = 0.025 moles

  3. Multiply moles by Avogadro's number: 0.025 moles * 6.022 x 10²³ atoms/mol ≈ 1.505 x 10²² atoms

(ii) What is the correct formula of calcium phosphate?

  • (a) CaPO₄

  • (b) Ca₂(PO₄)₃

  • (c) Ca₃(PO₄)₂ (This is the correct answer)

  • (d) CaP

Explanation:

  • Calcium ion (Ca²⁺) has a charge of +2.

  • Phosphate ion (PO₄³⁻) has a charge of -3.

  • To balance the charges, you need 3 calcium ions and 2 phosphate ions.

(iii) How many atomic mass units (amu) are there in one gram?

  • (a) 6.022 x 10²³ amu

  • (b) 1/6.022 x 10²³ amu

  • (c) 6.022 x 10²³ amu (This is the correct answer)

  • (d) 1 amu

Explanation:

  • Avogadro's number (6.022 x 10²³) is the number of amu in one gram.

(iv) Structural formula of 2-butene is CH₃-CH=CH-CH₃. What will be its molecular formula?

  • (a) C₂H₆

  • (b) C₃H₈

  • (c) C₄H₈ (This is the correct answer)

  • (d) C₄H₁₀

Explanation:

  • Count the carbons (C) and hydrogens (H) in the structural formula.

(v) How many moles are there in 23 g of NO₂?

  • (a) 0.25 moles

  • (b) 0.5 moles (This is the correct answer)

  • (c) 0.255 moles

  • (d) 1 mole

Explanation:

  1. Molar mass of NO₂: 14 (N) + 2 * 16 (O) = 46 g/mol

  2. Moles = mass / molar mass = 23 g / 46 g/mol = 0.5 moles

(vi) What is the number of atoms in 12 g of carbon?

  • (a) 6.022 x 10²³ atoms (This is the correct answer)

  • (b) 12.044 x 10²³ atoms

  • (c) 1.000 x 10²⁴ atoms

  • (d) 1.505 x 10²² atoms

Explanation:

  1. Molar mass of carbon: 12 g/mol

  2. Moles = 12 g / 12 g/mol = 1 mole

  3. 1 mole contains 6.022 x 10²³ atoms.

(vii) What is the most acidic of calcium oxide, H₂O, HCl, and NH₃?

  • (a) Calcium oxide

  • (b) H₂O

  • (c) HCl (This is the correct answer)

  • (d) NH₃

Explanation:

  • HCl (hydrochloric acid) is a strong acid.

(viii) When one mole of each of the following compounds is reacted with excess oxygen, which one produces the maximum amount of CO₂?

  • (a) Carbon

  • (b) Methane

  • (c) Ethane

  • (d) Propane (This is the correct answer)

Explanation:

  • Propane (C₃H₈) has the most carbon atoms, leading to the most CO₂ when combusted.

(ix) What mass of 15% CaCO₃ will be required to neutralize 30 cm³ of 0.5M HCl?

  • (a) 1g (This is the correct answer)

  • (b) 1.25g

  • (c) 1.43g

  • (d) 1.65g

Explanation:

  1. Moles of HCl: 0.5 mol/L * 0.03 L = 0.015 moles

  2. Moles of CaCO₃ required: 0.015 moles / 2 = 0.0075 moles

  3. Molar mass of CaCO₃: 100 g/mol

  4. Mass of CaCO₃: 0.0075 moles * 100 g/mol = 0.75 g

  5. Mass of 15% CaCO₃: 0.75 g / 0.15 = 5 g

2. Questions for Short Answers

(i) Write down the chemical formula of water.

  • H₂O

(ii) Find out the molecular formula of a compound whose empirical formula is CH₂O and molar mass is 180 g/mol.

  • Molecular formula: C₆H₁₂O₆ (Glucose)

Explanation:

  1. Empirical formula mass: 12 + 2(1) + 16 = 30 g/mol

  2. Ratio: 180 g/mol / 30 g/mol = 6

  3. Molecular formula: (CH₂O)₆ = C₆H₁₂O₆

(iii) How many molecules are present in 1.5 g of H₂O?

  • 5.018 x 10²² molecules

Explanation:

  1. Molar mass of H₂O: 18 g/mol

  2. Moles: 1.5 g / 18 g/mol = 0.0833 moles

  3. Molecules: 0.0833 moles * 6.022 x 10²³ molecules/mol ≈ 5.018 x 10²² molecules

(iv) What is the direct relationship between atoms and mass?

  • The relationship is through the concept of the mole and molar mass. The number of atoms is related to the number of moles, and the mass is related to the number of moles through the molar mass.

(v) Write down the chemical equation of the following reaction: Copper + Sulphuric acid → Copper sulphate + Sulphur dioxide + Water

  • Cu + 2H₂SO₄ → CuSO₄ + SO₂ + 2H₂O

3. Constructed Response Questions

(i) Different compounds will never have the same molecular formula but they can have the same empirical formula. Explain.

  • Explanation: The empirical formula represents the simplest whole-number ratio of atoms in a compound, while the molecular formula represents the actual number of atoms in a molecule. Different compounds can have the same simplest ratio but different actual numbers of atoms.

(ii) Write down the chemical formulas of the following compounds: Calcium phosphate, Aluminum nitrate, Sodium acetate, Ammonium carbonate.

  • Calcium phosphate: Ca₃(PO₄)₂

  • Aluminum nitrate: Al(NO₃)₃

  • Sodium acetate: NaC₂H₃O₂

  • Ammonium carbonate: (NH₄)₂CO₃

(iii) Why does Avogadro's number have an immense importance in chemistry?

  • Explanation: Avogadro's number (6.022 x 10²³) provides the link between the microscopic world of atoms and molecules and the macroscopic world of grams and moles. It allows us to relate the number of particles to the amount of substance.

(iv) When 88.67g of a compound were converted into elements, it gave 52.17g of carbon, 19.62g of hydrogen, and 16.88g of oxygen. Calculate the percentage of each element present in this compound.

  • % Carbon: (52.17 g / 88.67 g) * 100% = 58.8%


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