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Questions in chemistry

[Terjawab] Encircle T if the statement is true and F if it is false. 1. All mixtures are beneficial to humans. 2. Expiration dates placed in food and medicine must not be taken seriously. 3. Trails of plastic bags found in oceans is an example of a harmful form of mixture. 4. Researching about the substances that will be used in forming mixtures is not important. 5. An alloy is a type of solution made from combining two or more substances or metals.

[Terjawab] A. Fill in the blanks: 1. Substances that taste sour are generally ________. 2. A base has a ________ taste and feels ________. 3. ________ paper is used to determine whether a substance is acidic or basic. 4. Bases turn litmus paper to blue. B. Write True or False: 1. All acids taste bitter. 2. Bases are usually slippery to touch. 3. Vinegar is an example of a base. 4. Salt and water are the products of a neutralization reaction. C. Tick (/) the correct answer: 1. Which of these is a common household base? (a) Vinegar (b) Baking soda (c) Lemon juice (d) Water 2. What colour does blue litmus paper turn in the presence of an acid? (a) Red (b) Blue (c) Green (d) Yellow 3. Which of the following is an example of a neutral substance? (a) Salt (b) Baking soda (c) Lemon juice (d) Vinegar D. Match each term in Column A with the correct description in Column B. | Column A | Column B | |---|---| | 1. Acid | A. Changes colour in presence of acid or base | | 2. Base | B. Has a bitter taste and slippery feel | | 3. Neutralisation | C. Substance with a sour taste | | 4. Indicator | D. Reaction of acid with base | | 5. Salt | E. Product of neutralisation | E. Answer the following questions: 1. What is an indicator and why is it used in testing acids and bases? 2. Describe what happens to litmus paper when it is dipped into vinegar.

[Terjawab] 1. The substance which turns blue litmus red is (a) neutral (b) acidic (c) basic (d) alkaline 2. The acid present in curd/sour milk is (a) formic acid (b) acetic acid (c) lactic acid (d) hydrochloric acid 3. H₂SO₄ is (a) an acid (b) a salt (c) a base (d) an alkali

[Terjawab] 14. A complete combustion of a hydrocarbon forms 1.10 g of CO2 and 0.45 g of H2O. The molar mass is 84.00 g mol-1. Determine the empirical formula and molecular formula of the hydrocarbon.

[Terjawab] The molecular mass of sodium oxide $(Na_2O)$ is A) 45.97954. B) 61.97894. C) 22.98977. D) 38.98917.

[Terjawab] What happened when you mixed certain materials like baking soda and lemon?

[Terjawab] Using the steps above, a solution of sodium carbonate reacts with a solution of sulphuric acid to produce sodium sulphate, carbon dioxide, and water. a. Write the ionic equation for this reaction. b. Identify the spectator ions in this reaction. Balance the equation below and write its ionic equation. [tex]CaCO_3(s)+HCl(aq) \longrightarrow CaCl_2(aq)+CO_2(g)+H_2 O(l)[/tex]

[Terjawab] Consider the following intermediate chemical equations: [tex] \begin{array}{l} C(s)+\frac{1}{2} O_2(g) \rightarrow CO(g) \\ CO(g)+\frac{1}{2} O_2(g) \rightarrow CO_2(g) \end{array} [/tex] How will oxygen appear in the final chemical equation? A. [tex]O _2(g)[/tex] as a product B. [tex]O _2(g)[/tex] as a reactant C. [tex]O ( g )[/tex] as a product D. [tex]2 O ( g )[/tex] as a reactant

[Terjawab] Which of these is a chemical property of a substance? A. texture B. ductility C. reactivity D. conductivity

[Terjawab] Use atomic diagrams to show how a covalent bond is formed between 3 hydrogen atoms and 1 nitrogen atom to form NH3.