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Questions in chemistry

[Done] Which of the following represents a pair of isotopes? A. $O _2, O _3$ B. ${ }_6^{14} C ,{ }_7^{14} N$ C. all are pairs of isotopes D. ${ }_1^1 H ,{ }_1^2 H$ E. ${ }_{16}^{32} s,{ }_{16}^{32} s^{-2}$

[Done] 4.1 What leads to the formation of new substances during chemical reactions? 4.2 Do you agree with the following statements? Justify your answers. (a) A change can be either physical or chemical but can never be both. (b) All kinds of changes involve chemical reactions.

[Done] 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] When you form the final chemical equation, what should you do with CO? A. Cancel out CO because it appears as a reactant in one intermediate reaction and a product in the other intermediate reaction. B. Add the two CO molecules together and write them as reactants in the final chemical reaction. C. Write CO only once as a reactant in the final chemical reaction. D. Write CO as a reactant and a product in the final chemical reaction.

[Done] Which molecule is a stereoisomer of trans-2-butene? A. B. C. D.

[Done] Consider the reaction below. [tex]$C_2 H_4(g)+H_2(g) \rightarrow C_2 H_6(g)$[/tex] Which change would likely cause the greatest increase in the rate of the reaction? A. decrease temperature and decrease pressure B. increase temperature and decrease pressure C. decrease temperature and increase pressure D. increase temperature and increase pressure

[Done] The table describes the properties of four compounds. | Property | A | B | C | D | | ----------------------------- | ---- | ------------------ | --- | ---- | | Melting point | High | | Low | High | | Boiling point | High | Low | Low | High | | Does the compound dissolve in water? | Yes | Yes | Yes | Yes | | Can the compound conduct electricity? | Yes | Yes, but poorly. | No | Yes | Which compounds are most likely ionic? A. compounds A and B B. compounds B and C

[Done] [CU(H_2O)_4]^{2+} + H_2O \rightleftharpoons Write the equation for the following acting as an acid.

[Done] An atom with [tex]$Z=26$[/tex] and [tex]$A=58$[/tex] contains protons and neutrons. A. 26; 84 B. 26; 58 C. 58; 26 D. 26; 32 E. 32; 26

[Done] Magnesium is an example of a(an) A. alkali metal. B. transition metal. C. halogen. D. noble gas. E. alkaline earth.

[Done] [Cu(H_2O)_4]^{2+} + H_2O. Write the equation for the following species acting as an acid.