BMAT Prep Question Analysis - Q171 & Q245
Q171 Zn and Cu² undergo an equimolar redox reaction, whereby Zn2+ is formed. After the reaction, what is the oxidation number of Cu?
a. 1
b. 0
c. -1
d. 2
e. -2
Q245 In the figure below, the square ABCD and the triangular region ACE each have area 36.
Which is the perimeter of the triangle ACD?
Answer and Explanation
Q171 Answer: b. 0
Explanation: This equimolar redox (reduction-oxidation) reaction, 2 electrons are traded between these two metals. Since zinc loses 2 electrons, that must mean that Cu?* gains 2 electrons in the reaction and forms an uncharged Cu atom. The oxidation number of a monoatomic species is equal to its net charge (zero in this case)
Q245 Answer: b. 12 + 6√2
Explanation: Since the area of square ABCD is 36, we deduce that each side of the square measures √36 = 6. We fherefore now know that AD = CD = 6.
The distance AC is calculated using the Pythagorean theorem and is equal to √(36 + 36) i.e. √72 or 6√2.
Thus the perimeter of the triangle ACD is 6+6+6√2 = 12+ 62. Note that the information given about ACE is not needed to solve this question.
Drafted by Quincy (BMAT Prep)