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Questions in chemistry

[Terjawab] Decide whether each pair of elements in the table below will form an ionic compound. If they will, write the empirical formula of the compound formed in the space provided. | element #1 | element #2 | Forms ionic compound? | empirical formula of ionic compound | |---|---|---|---| | potassium | fluorine | | | | oxygen | cesium | | | | barium | cesium | yes no | | | bromine | oxygen | yes no | |

[Terjawab] What's mass? A) A measure of an element's attraction for electrons B) The force that gravity exerts upon an object C) The sum of the number of protons and neutrons in an atom D) A measure of the amount of matter an object contains

[Terjawab] If you are measuring how water chemistry changes in a river in the days after a flood, the time measurement is the A. independent variable. B. independent constant. C. dependent variable. D. dependent constant.

[Terjawab] The equation for the pH of a substance is [tex]$pH =-\log \left[ H ^{+}\right]$[/tex], where [tex]$H +$[/tex] is the concentration of hydrogen ions. What is the approximate pH of a solution if the concentration of hydrogen ions is [tex]$5.0 \times 10^{-4}$[/tex] moles per liter? A. 2.7 B. 3.0 C. 3.3 D. 3.6

[Terjawab] Which clue can be used to identify a chemical reaction as a decomposition reaction? A. The reaction involves oxygen. B. The reaction involves ions. C. The reaction has a single reactant. D. The reaction has a single product.

[Terjawab] At [tex]$60^{\circ} C$[/tex] 124 g of saturated solution obtained 2 g of solid [tex]$A$[/tex] 12 g of saturated solution obtained = ? [tex]\begin{array}{l} =\frac{12 g \times 2 g}{124 g} \\ =2.32 g \end{array}[/tex]

[Terjawab] How many moles are in [tex]$2.11 \times 10^{24}$[/tex] molecules of [tex]$BeF _2$[/tex]?

[Terjawab] Which reference is most appropriate for handling specific chemical agents safely? A. Red book B. Owner's Manual C. Drug Index D. Safety Data Sheet (SDS)

[Terjawab] Why are covalent compounds considered non-conductive and non-electrolytes? A. They have high flexibility. B. They are insulators. C. They contain ions. D. They are metals.

[Terjawab] Write the chemical symbol for an element belonging to each of the element families in the table below. | element family | example element | | --- | --- | | halogen | $\square$ | | chalcogen | $\square$