This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the solutions to the questions: 15. What is the shape of CCl_4 molecule? Step 1: Carbon (C) is the central atom, and it forms single bonds with four chlorine (Cl) atoms. Step 2: Carbon has 4 valence electrons, and it uses all of them to form 4 single bonds, resulting in 4 bonding pairs and 0 lone pairs around the central carbon atom. Step 3: According to VSEPR theory, a molecule with four electron domains and no lone pairs has a tetrahedral molecular geometry. The correct option is B. B. Tetrahedral 16. A mixture of diamond and iron filings can be separated by Step 1: Diamond is a form of carbon and is non-magnetic. Step 2: Iron filings are magnetic. Step 3: Mixtures containing magnetic and non-magnetic components can be separated using a magnet. This process is called magnetisation. The correct option is C. C. magnetisation 17. The percentage of oxygen in sulphur (IV) oxide is [S=32, O=16] Step 1: Sulphur (IV) oxide is SO_2. Step 2: Calculate the molar mass of SO_2: Molar mass of S = 32 g/mol Molar mass of O = 16 g/mol Molar mass of SO_2 = 32 + (2 × 16) = 32 + 32 = 64 g/mol. Step 3: Calculate the total mass of oxygen in SO_2: Mass of oxygen = 2 × 16 = 32 g. Step 4: Calculate the percentage of oxygen: Percentage of oxygen = mass of oxygenmolar mass of SO_2 × 100\% = (32)/(64) × 100\% = 0.5 × 100\% = 50\%. The correct option is D. D. 50. 18. The metal that does not react with oxygen is Step 1: This question asks about the reactivity of metals with oxygen. Metals vary in their reactivity, with some reacting readily and others being very unreactive. Step 2: Among the given options, silver (Ag) is a noble metal known for its low reactivity. It does not readily react with oxygen under normal conditions, unlike aluminum (Al), magnesium (Mg), lead (Pb), and tin (Sn), which all form oxides. The correct option is A. A. Ag 19. The following are chemical changes except Step 1: A chemical change results in the formation of new substances with different chemical properties. A physical change alters the form or appearance but not the chemical composition. Step 2: • Fading of coloured cloth involves the chemical breakdown of dye molecules. • Fermentation of glucose converts glucose into ethanol and carbon dioxide. • Rusting of iron nails involves iron reacting with oxygen and water to form iron oxide. • Slaking of quicklime involves calcium oxide reacting with water to form calcium hydroxide. • Sublimation of solids is a phase change where a solid turns directly into a gas without passing through a liquid state (e.g., dry ice turning into carbon dioxide gas). No new chemical substance is formed. The correct option is E. E. sublimation of solids 20. The bond involved in the formation of a hydroxonium ion is that of Step 1: A hydroxonium ion (H_3O^+) is formed when a water molecule (H_2O) accepts a proton (H^+). Step 2: The oxygen atom in water has two lone pairs of electrons. The H^+ ion (which has no electrons) forms a bond by accepting both electrons from one of these lone pairs. Step 3: A bond formed when one atom donates both electrons to the shared pair is called a dative bond or coordinate covalent bond. The correct option is B. B. dative 21. Reduction can be defined as Step 1: Reduction is one half of a redox (reduction-oxidation) reaction. Step 2: Common definitions of reduction include the gain of electrons, a decrease in oxidation state, the gain of hydrogen, or the loss of oxygen. Step 3: Among the given options, "addition of hydrogen" is a correct definition of reduction. The correct option is B. B. addition of hydrogen. 22. Linear molecules have a bond angle of Step 1: A linear molecular geometry means that the atoms are arranged in a straight line. Step 2: For atoms to be in a straight line, the angle between the bonds must be 180^. Examples include CO_2 and BeCl_2. The correct option is E. E. 180^ 23. Which of the following ions has the same electronic structure as argon? Step 1: Argon (Ar) is a noble gas with atomic number 18. Its electronic configuration is 1s^2 2s^2 2p^6 3s^2 3p^6, meaning it has 18 electrons. Step 2: We need to find an ion that also has 18 electrons. • F^- (Fluorine, atomic number 9) has 9+1=10 electrons. • Al^3+ (Aluminum, atomic number 13) has 13-3=10 electrons. • Na^+ (Sodium, atomic number 11) has 11-1=10 electrons. • Mg^2+ (Magnesium, atomic number 12) has 12-2=10 electrons. • Cl^- (Chlorine, atomic number 17) has 17+1=18 electrons. The correct option is E. E. Cl^- 24. Which of the following elements is the most electronegative? Step 1: Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. Step 2: Electronegativity generally increases across a period and decreases down a group in the periodic table. Step 3: All the given elements (Astatine, Bromine, Chlorine, Fluorine, Iodine) are halogens (Group 17). Within Group 17, electronegativity decreases as you go down the group. Fluorine is at the top of the group, making it the most electronegative element among the options (and the most electronegative element overall). The correct option is D. D. Fluorine 3 done, 2 left today. You're making progress.