1. Which of the following generally indicates the possibility of a chemical chan
ID: 1043943 • Letter: 1
Question
1. Which of the following generally indicates the possibility of a chemical change? i. Color change ii. Formation of a solid iii. Formation of a gas iv. Absorption or release of heat energy v. Emission of light energy Intr A. All B. All but i C. All but ii Wh D. All but i E. All but v 2. Which of the following chemical equations are balanced correctly? i. MgCl(aq)+2 RbF(aq)-> MgF(s)+2 RbCl(aq) ii. C3Hs(e) +5 02(g) 3 CO2(g)+4 HO(g) iii. 2 CsHioo()15 O2(g) 10 CO2(g) +10 H,00) A. i only B. i and ii C. i and ii D. ii and ii E. i, i, and ii 3. Consider the hypothetical chemical reaction represented by the equation 2 A+3 B->A,B, Which of the following is a correct interpretation of this equation? i. 2 grams of A react with 3 grams of B to form 1 gram of A2B, ii. 2 atoms of A react with 3 atoms of B to form 1 molecule of A2B ???. 2 moles ofA react with 3 m oles of B to form 1 mole ofA2B, D. ii and iii E. i, i, and ii A. i onlyB. ii only C. ii onlyExplanation / Answer
1) A)All
i) color changes= example reaction between copper and oxygen forms copper oxide .statue is covered in layer of copper which is shiny brown metal this layer of copper has gone chemical reactions the copper turn green
ii)formation of solid= example mixture of clear solution of silver nitrate and sodium chloride,silver chloride forms precipitation
iii)formation of gas= example decomposition reaction that breaks water into hydrogen and oxygen gas
iv)absorption and release of heat energy=example exothermic reactions gives off heat.endothermic reaction absorb heat.
v)emission of light energe= example phosphorus in the presence of oxygen burns spontaneously producing flame.
2) B) i and ii
in any chemical equvation reactant side molecule and product side molecule are always equval .that reaction is balance reaction hence i and ii reaction is balance reaction.
3) D) ii and iii only
left side is reactant and right side is product side of reaction.reactant and product are in mole or atom forms
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