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Questions in chemistry

[Terjawab] Consider the nuclear equation below. ${ }_{66}^{222} Rn \longrightarrow{ }_{84}^{210} Po+{ }_2^4 He$ Which is the missing value that will balance the equation? A. 84 B. 86 C. 88 D. 90

[Terjawab] Which property of a substance can be determined using a pH indicator? A. acidity B. boiling point C. density D. electrical conductivity E. thermal conductivity

[Terjawab] What is the natural state of mercury, Hg? A. solid B. gas C. liquid

[Terjawab] Select all the correct answers. Which equations represent precipitation reactions? [tex]$Na _2 S+ FeBr _2 \rightarrow 2 NaBr + FeS$[/tex] [tex]$MgSO _4+ CaCl _2 \rightarrow MgCl _2+ CaSO _4$[/tex] [tex]$LiOH + NH _4 I \rightarrow Lil + NH _4 OH$[/tex] [tex]$2 NaCl + K _2 S \rightarrow Na _2 S+2 KCl$[/tex] [tex]$AgNO _3+ NaCl \rightarrow AgCl + NaNO _3$[/tex]

[Terjawab] Test your understanding of isotopes by selecting the correct relationship between the pair of atoms ${ }_6^{13} C$ a Isotopes b Different Element c Same Atom, Not Isotopes of Each Other

[Terjawab] Which is the electron configuration for lithium? A. $1 s^2$ B. $2 s^3$ C. $1 s^2 2 s^1$ D. $1 s^1 2 s^2$

[Terjawab] All except one is not a safety rule. A. Report all accidents and breakages to your teacher. B. Run and push other people or behave in a rough way. C. Always check the label on the bottle before using the contents. D. You are not permitted in a science laboratory when your instructor is not with you. It can be caused by breathing in fumes and by tasting or by spilling them into your skin. A. Cuts B. Poisoning C. Damage to the laboratory D. Damage to clothing and skin For holding test tubes containing liquids or solid A. ill B. IV C. III D. VI For filtering A. 1 B. II C. IV D. IV For attaching clamp to stand A. I B. 11 C. IV D. VI Used to contain chemical reactions. A. 11 B. III C. IV D. V A three-legged platform used to support flasks and beakers. A. III B. IV C. V D. VI For cleaning test tubes A. 11 B. III C. IV D. V Scientists often investigate things by first thinking of a hypothesis, and then testing it by doing A. prediction B. conclusion C. hypothesis D. experiments

[Terjawab] AgNO_3(aq) + KCl(aq) \rightarrow AgCl(s) + KNO_3(aq) Which of the following describes this reaction? A. precipitation B. acid-base neutralization C. redox reaction

[Terjawab] Select the correct answer. This chemical equation is not balanced: [tex]$\operatorname{AgBr}(s) \rightarrow Ag(s)+Br_2(g)$[/tex] Why isn't it possible for the reaction to occur as indicated by the unbalanced equation? A. There are more substances on the right side of the equation than on the left side. B. There is a gas on the right side of the equation but not on the left side. C. The bromine atoms must go through a liquid state before becoming a gas D. There is more mass represented on the right side of the equation than on the left side. E. The bromine atoms on the right side of the equation are not bonded to another element.

[Terjawab] The symbol for a radioactive nuclide is ${ }_{56}^{131} Ba$. Which statement is correct? A. The atomic number of the radioactive nuclide is 75. B. The mass number of the radioactive nuclide is 131. C. The number of neutrons that are present in the nucleus of each atom is 56. D. The number of protons that are present in the nucleus of each atom is 131.