Cho 10,2 gam hỗn hợp A gồm Mg và Al phản ứng vừa đủ với dung dịch H2SO4 19,6%, sau phản ứng thu được 11,2 lit H2( đktc) a. Tính % khối lượng mỗi kim loại trong A.
b. Tính khối lượng dung dịch H2SO4 cần dùng.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

here is table 2-2:

country

percent of eligible voters that voted

rank

united states

44.9%

138

canada

60.1%

107

costa rica

84.6%

14

hungary

66.9%

82

japan

57.0%

118

egypt

27.7%

159

south africa

85.5%

10

ans is no, the data set cannot be plotted as a single circle graph