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Questions in chemistry

📝 Answered - Which of the following is not a correct perspective representation of a stereoisomer of 2,3-dibromobutane? A. B. C. D.

📝 Answered - What is the difference between concentrated and dilute acids? When diluting acids, why do we always add the acid slowly to the water?

📝 Answered - Elements with 1, 2, or 3 valence electrons usually make excellent... (a) Neutral (b) insulators (c) semiconductors (d) conductors

📝 Answered - Convert structures 1 and 2 Newman projections to the corresponding line-angle formula. Determine the appropriate IUPAC name for each formula. Structure 1 Structure 2 Which of the following is correct? A. 2-methylpentane B. n-propane C. 2,2-dimethylbutane D. 3-methylpentane E. 2-methylpropane

📝 Answered - Which of the following choices is/are true about the following compounds: I. II. III. IV. a. the following is the correct order of decreasing reactivity toward HBr addition: III > II > IV>I b. all the above compounds are unsaturated hydrocarbons c. the following is the correct order of increasing reactivity toward HBr addition: I d. all the above compounds have the same reactivity toward HBr addition e. compound I does not undergo addition reaction under any condition

📝 Answered - Which type of reaction has the general formula of [tex]A B+C D \rightarrow A D+C B[/tex] ? synthesis decomposition oxidation replacement

📝 Answered - A solid precipitate is formed from the reaction of lead nitrate and sodium chromate. What would be the best method to separate this solid from the solution? A. distillation B. evaporation C. filtration D. sorting

📝 Answered - Which of these materials is most effective against chemical hazards? A. Cloth B. Leather C. Rubber D. Mesh

📝 Answered - A balloon containing helium gas expands from 230 mL to 860 mL as more helium is added. What was the initial quantity of helium present if the expanded balloon contains $3.8 \times 10^{-4} mol$, assuming constant temperature and pressure? Use the formula: $\frac{V_1}{n_1}=\frac{V_2}{n_2}$ A. $1.0 \times 10^{-4} mol^6$ B. $1.5 \times 10^{-4} mol$ C. $1.0 \times 10^{-3} mol$ D. $1.4 \times 10^{-3} mol$

📝 Answered - 1. Choose the condition in which a silver cup will tarnish. A. Presence of sulphur in air and coated with oil B. Presence of oxygen in air and coated with oil C. Presence of sulphur in air and coated with water D. Presence of oxygen in air and coated with grease 2. Explain with an example why corrosion is a harmful chemical process and write 2 ways to prevent it. 3. Which place is likely to have a greater chance of corrosion - a place with 40% humidity or a place with 60% humidity? Give reasons for your answer.