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Questions in chemistry

[Terjawab] The chemical symbol for the element calcium is Ca. What would be the symbol representing calcium atoms that Ca [tex]Ca ^{+}[/tex] [tex]Ca ^{-2}[/tex] [tex]Ca ^{+2}[/tex]

[Terjawab] Which of the following is a correct empirical formula if the ratio of compounds is [tex]$2: 1: 3$[/tex]? A. [tex]$Na _2 SO _3$[/tex] B. [tex]$K _2 C _2 O _3$[/tex] C. [tex]$Ca _3( OH )_2$[/tex] D. [tex]$CF _2 Cl _2$[/tex]

[Terjawab] The electrolytic cell shown below is used for the electrolysis of CuCl2 solution. A | | | | | | ----- B CuCl2 (aq) A and B are carbon electrodes. 9.1 Define electrolysis. 9.2 Is the process of electrolysis EXOTHERMIC or ENDOTHERMIC? 9.3 Write down the half reaction that occurs at electrode B. 0.369 g of Cu is deposited on the cathode in 27 minutes. 9.4 Calculate the electrical current used during this process.

[Terjawab] What is crude oil? (ii). State four effects of petrochemicals on the environment.

[Terjawab] The equation below shows a reaction that produces calcium carbonate. [tex]Ca(OH)_2(s)+CO_2(g) \rightarrow CaCO_3(s)+H_2 O(l)[/tex] Which describes a way to speed up the collisions between calcium hydroxide and carbon dioxide molecules to produce calcium carbonate faster? A. Lower the temperature. B. Use larger pieces of calcium hydroxide. C. Lower the pressure. D. Reduce the volume of the container.

[Terjawab] Which of the following potentially cancerous compounds are found in AFFF? A. Primary carbons B. Perforated carbons C. Purified carbons D. Perfluorinated carbons Foam prevents potential flammable sources from igniting and extinguishes already burning fuel so A. reducing fuel temperature B. suppressing flammable vapors C. preventing oxygen from contacting the fuel source D. forming a blanket layer over the combustible liquids E. reacting with the fuel source to change its chemical composition

[Terjawab] Which of the following correctly shows an ion pair and the ionic compound the two ions form? A. [tex]$Sn ^4, N^3: Sn _4 N_3$[/tex] B. [tex]$Cr ^{3+}, 1$ : Cr1[/tex] C. [tex]$Cu ^{2+}, O ^{2-} ; Cu _2 O _2$[/tex] D. [tex]$Fe ^{3+} \cdot O ^{2-}: Fe _2 O _3$[/tex]

[Terjawab] Select the most likely product for this reaction: [tex]KOH ( aq )+ CO _2(g) \rightarrow[/tex] ? A. [tex]K _2 CO _3( aq )+ H _2 O ( l )[/tex] B. [tex]K ( s )+ H _2(g)+ O _2(g)[/tex] C. [tex]K ( s )+ CO _3(g)+ H _2[/tex]

[Terjawab] If we have a sample of silicon $(Si)$ atoms that has 14...

[Terjawab] The picture shows a wooden bowl. The pieces of wood used for this bowl were dyed different colours. The artist who made the bowl explained why he dissolved the coloured dyes in methanol. I use different coloured dyes dissolved in methanol. I use methanol because with dyes dissolved in water the wood needs to be soaked for a longer time. The bowl dries more quickly if I use methanol instead of water. (a) The artist uses methanol instead of water. Give two reasons why. 1. 2.