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Questions in chemistry

[Homework Help] Which substance is a compound? A. water B. gold C. oxygen D. hydrogen

[Homework Help] $3 O _2(g) \longleftrightarrow 2 O _3(g)$ At 298 K, the equilibrium concentration of $O _2$ is $1.6 \times 10^{-2} M$, and the equilibrium concentration of $O _3$ is $2.86 \times 10^{-28} M$. What is the equilibrium constant of the reaction at this temperature? A. $2.0 \times 10^{-50}$ B. $2.0 \times 10^{50}$ C. $1.8 \times 10^{-26}$ D. $1.8 \times 10^{26}$

[Homework Help] 4.1 The ammonium ion (NH4+) is formed when an ammonia molecule (NH3) reacts with a hydrogen ion (H+). Describe the formation of the dative covalent bond in the ammonium ion. Use Lewis diagrams to aid your explanation. (4) 4.2 The hydronium ion (H3O+) is another example of a species containing a dative covalent bond. a) Draw Lewis structures to show the formation of the hydronium ion from a water molecule and a hydrogen ion. (4) b) Name the molecule that provides the lone pair for the dative covalent bond in the formation of H3O+. (1) c) How many covalent bonds are present in a hydronium ion? (1) QUESTION 5: ELECTRONEGATIVITY & BOND POLARITY (18 MARKS) Use the table of electronegativity values below to answer the questions that follow: | Element | Electronegativity (Pauling scale) | |---|---| | H | 2.1 | | C | 2.5 | | N | 3 | | O | 3.5 | | F | 4 | | Na | 0.9 | | Cl | 3 | | Br | 2.8 | 5.1 Define electronegativity. (2) 5.2 What is the difference between a non-polar covalent bond and a polar covalent bond? Refer to the sharing of electrons in your answer. (3)

[Homework Help] The rate of a certain reaction depends on concentration according to the equation: -\frac{dc}{dt} = \frac{K_1 C}{1 + K_2 C} What will be the order of reaction when concentration C is very low?

[Homework Help] Please answer the following test questions: 1. Class A fires typically will require which type of foam? A. Low expansion foam B. Mid expansion foam C. High expansion foam D. Super expansive foam Which of the following foams is best suited for direct attack?

[Homework Help] Which is the best definition of activation energy? A. the energy required to end a chemical reaction B. the energy required to bind a substrate to an active site C. the energy required to form or break the bonds of reactant molecules D. the energy required to re-form bonds in product molecules

[Homework Help] What ability did the PFAS-containing sandwich wrappers have? A. Grease repelling B. Biodegradability C. Waterproofing D. Heat resistance

[Homework Help] Write T for True and F for False statements. Melamine and Bakelite are examples of thermoplastics. Plastics are soluble in water. PET is used for making sanitary fittings. The harmful effects associated with plastic disposal are reducing the usage of plastics.

[Homework Help] What is the basic unit of matter? A. atom B. molecule C. gas D. compound

[Homework Help] The main acid in the stomach is hydrochloric acid $(HCl)$. Which chemical equations show a reaction that occurs when someone takes an antacid? Check all that apply. $HCl + NaOH \rightarrow NaCl + H_2O$ $2 HCl + CaCO_3 \rightarrow CaCl_2+ CO_2+ H_2O$ $2 HCl + Mg(OH)_2 \rightarrow MgCl_2+2 H_2O$ $6 HCl +2 Al \rightarrow 2 AlCl_3+3 H_2$ $HCl + NaHCO_3 \rightarrow NaCl + H_2O + CO_2$