Numerade

Questions asked

ANSWERED

Tavis Lam

Numerade educator

For each statement below: • Identify the mode/type of natural selection (directional/disruptive/stabilizing) • State the characteristics “selected for” and “selected against” (Note: assume that the intermediate trait is most numerous in the initial population…but remember in nature this is NOT always true!) (a) The hollow bones of birds have developed over time to enable flight to be more effective (b) The evolution of a giraffe’s long neck (c) The smell of a skunk has become more potent compared to the past (d) The body diameter of snakes has stayed constant over time (e) The evolution of beak size in birds on an island with very large and very small seeds (f) The development of antibiotic resistant bacteria (g) The consistent colour of blue jays over several decades (h) The evolution of light and dark insects on an island with a forest and a meadow

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ANSWERED

Joanna Quigley

Numerade educator

3. Match graphs \( \mathrm{a}, \mathrm{b} \), and c of \( \mathrm{y}=\mathrm{f}(\mathrm{x}) \) with their corresponding derivatives, graphs \( \mathrm{A}, \mathrm{B} \), and C . (3) a) A a) B b) c) c) C 4. Identify whether each situation represents average rate of change or instantaneous (5) rate of change. a) Jordan grew 8 cms in 15 months b) The temperature of the pool dropped by 10 degrees overnight c) At 4 pm the speed of the car was \( 5 \mathrm{~km} / \mathrm{hr} \) d) When the radius of a circular ripple on the surface of a pond is 4 cm , the circumference of the ripple is increasing at \( 21.5 \mathrm{~cm} / \mathrm{s} \). e) A stock price drops \( 30 \% \) in four weeks.

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INSTANT ANSWER

1. In an investigation, 50 g of potassium chloride is added to 100 g of water at 60 °C. The mixture is stirred until no more potassium chloride dissolves. Use the graph in Figure 1 to answer the following questions. 2. Use Figure 1, above, to consider the solubilities of potassium nitrate and potassium chloride. (8.5) (a) Which solute is more soluble at 15 °C, potassium nitrate or potassium chloride? Explain your answer. At 15°c according to the graph, the solubility of Potassium nitrate (KNO;) is arcund 25 g per l0og ofwater Potassium Chloride (kCI) is around 32gper 100 g of water : kcl is more sowble at 1s°C. (a) Is the solution saturated or not? Explain how you know. (b) At what temperature are potassium nitrate and potassium chloride equally soluble? From the graph, the salubility CuNes of KNoz and kcl intersect at approximately 220c. making them equally soluble then (c) At what temperature(s) is potassium nitrate more soluble than potassium chloride?

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Solubility Curves of Ionic Compounds in Water

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1. In an oil-and-water mixture, dispersants break up oil into small droplets. 2. Changes in pressure significantly affect the solubility of a solid in a liquid 3. Molar concentration-is the correct IUPAC name for solution concentration. 4. A standard solution is a solution of known concentration. 5. Avotumelric pipette can delivera range of volumes. graduated 6. Aqueous solutions with extremely low concentrations have a density equal to the density of water. 7: Liquids that are immiscible with each other mix in all proportion

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ANSWERED

Ivan Kochetkov

Numerade educator

The number of moles of molecules in 71.6 g of methane, CH4(molar mass = 16.0 g/mol) is

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INSTANT ANSWER

1. Consider the following equation: \( \mathrm{Al}_{2} \mathrm{O}_{3}+\mathrm{H}_{2} \rightarrow \mathrm{Al}+\mathrm{H}_{2} \mathrm{O} \) When this equation is correctly balanced, the coefficient of a. \( \quad \mathrm{Al}_{2} \mathrm{O}_{3} \) will be 2 d. d. \( \mathrm{H}_{2} \) will be 2 b. \( \quad \mathrm{Al}_{2} \mathrm{O}_{3} \) will be 3 e. e. \( \mathrm{H}_{2} \mathrm{O} \) will be 3 c. \( \quad \mathrm{H}_{2} \) will be 1 2. The molar mass of copper(II) sulfate pentahydrate, \( \mathrm{CuSO}_{4} \cdot \mathbf{5 H}_{2} \mathrm{O} \), is a. \( \quad 245.6 \mathrm{~g} / \mathrm{mol} \) d. \( \quad 241.5 \mathrm{~g} / \mathrm{mol} \) b. \( \quad 177.5 \mathrm{~g} / \mathrm{mol} \) e. \( \quad 249.6 \mathrm{~g} / \mathrm{mol} \) c. \( \quad 219.2 \mathrm{~g} / \mathrm{mol} \) 3. The number of atoms present in 0.062 mol of acetic acid( \( \mathrm{CH}_{3} \mathrm{COOH} \) )is a. \( \quad 7.5^{\prime} \times 10^{22} \) atoms d. \( \quad 6.0 \times 10^{23} \) atoms b. \( \quad 3.8 \times 10^{22} \) atoms e. \( \quad 4.4 \times 10^{22} \) atoms c. \( \quad 1.5 \times 10^{23} \) atoms

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1. Which of the following will not result in a chemical reaction? (a) Aluminum is dipped into a zinc nitrate solution. (b) Zinc is added to a solution of copper(II) sulfate. (c) Lead is placed into an iron(III) solution. (d) Sodium is placed into cold water.

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INSTANT ANSWER

19. Every winter, mercury disappears from the Arctic atmosphere. True or False 20. A hydrocarbon is one type of organic compound. True or False

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1. Gaseous hydrogen chloride, HCl(g), reacts with ammonia gas, NH3(g), to form ammonium chloride, NH4Cl(s). (a) Is this reaction a neutralization reaction? Explain your answer. (b) Think about what forms when hydrogen chloride is added to water. Then think about the product of ammonia and water. How does this reaction differ if both gases are added to water before they react? 2. Four atoms of phosphorus can produce only 2 molecules of diphosphorus trioxide, even when plenty of oxygen atoms are present. (a) Write the chemical equation describing the reaction. (b) Explain why no more than 2 molecules of diphosphorus trioxide are produced for every 4 atoms of phosphorus.

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Andriy M.