Question

1. which of the following properties is exhibited by the ions listed: al³⁺, mg²⁺ and na⁺? a. allotropy b. isoelectronic c. isotopy d. isomerism 44. giant macromolecules contain a. ionic bonds. b. metallic bonds. c. covalent bonds. d. dative bonds. 45. which of the following compounds would produce a fruity scent when warmed with ethanol and concentrated h₂so₄? a. ch₃ch₂oh b. ch₃ch₂cooh c. ch₃ch₂cl d. ch₃ch₂nh₂ 46. which of the following statements about non - electrolytes are correct? i. they do not conduct electricity. ii. they are covalent substances. iii. they do not form ions. a. i and ii only b. ii and iii only c. i and iii only d. i, ii and iii 47. the percentage of oxygen in c₆h₁₂o₆ is a. 40.0 %. b. 53.3 %. c. 41.4 %. d. 55.2 %. 48. a substance which could be added to lemon juice to increase its ph is a. bromine water. b. oxalic acid. c. ethanoic acid. d. baking powder.

Explanation:

Question 43:

Al³⁺, Mg²⁺ and Na⁺ have the same number of electrons (10 electrons), which means they are isoelectronic. Allotropy refers to different forms of an element, isotopy is about different isotopes of an element, and isomerism is about compounds with same formula but different structures.

Question 44:

Giant macromolecules like polymers and network - solids are held together by covalent bonds. Ionic bonds are in ionic compounds, metallic bonds in metals, and dative bonds are a special type of covalent bond but not characteristic of giant macromolecules in general.

Question 45:

Esters have a fruity scent. When a carboxylic acid reacts with an alcohol in the presence of concentrated sulfuric acid, an ester is formed. CH₃CH₂COOH (a carboxylic acid) will react with ethanol to form an ester.

Question 46:

Non - electrolytes do not conduct electricity because they do not form ions in solution. Most non - electrolytes are covalent substances. So all three statements (I, II, III) are correct.

Question 47:

The molar mass of C₆H₁₂O₆ is \(6\times12 + 12\times1+6\times16=180\ g/mol\). The mass of oxygen in C₆H₁₂O₆ is \(6\times16 = 96\ g/mol\). The percentage of oxygen is \(\frac{96}{180}\times100\%\approx53.3\%\).

Question 48:

Lemon juice is acidic. Baking powder (sodium bicarbonate) is a base. Adding a base to an acid will increase the pH. Bromine water is an oxidizing agent, oxalic acid and ethanoic acid are acids, and they will not increase the pH of lemon juice.

Answer:

1. B. Isoelectronic
2. C. covalent bonds
3. B. CH₃CH₂COOH
4. D. I, II and III
5. B. 53.3%
6. D. baking powder