January 2012 Chemistry Regents #31-40

Highlight to reveal answers and explanations

 

Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50 Questions 51-54 Questions 55-57 Questions 58-59 Questions 60-62 Questions 63-65 Questions 66-69  Questions 70-71  Questions 72-74 Questions 75-78  Questions 79-81  Questions 82-85

 

Other Regents Exams

Questions

Answer Link Explanations

31 What is the total number of valence electrons in a germanium atom in the ground state?

(1) 22       (3) 32

(2) 2         (4) 4

4

link

 

2-8-18 -4  <----

last number of the electron configuration on the Periodic table

32 Which element is paired with an excited-state electron configuration for an atom of the element?

(1) Ca: 2-8-8-2     (2) Na:   2-8-2

(3) K: 2-6-8-3       (4) F:  2-8

3 link excited states have an electron that has jumped up

K should be 2-8-8-1  (ground state)

 

33 Given the balanced equations representing two chemical reactions:

Cl2 + 2NaBr ---> 2NaCl + Br2

2NaCl---> 2Na + Cl2

Which types of chemical reactions are represented by these equations?

(1) single replacement and decomposition

(2) single replacement and double replacement

(3) synthesis and decomposition

(4) synthesis and double replacement

 
1 link see link

 

34 An ion that consists of 7 protons, 6 neutrons, and 10 electrons has a net charge of

(I ) 4-     (3) 3+

(2) 3-      (4) 4+

3 link the charge is the difference between the positive protons and negative electrons

 

35 Which Lewis electron-dot diagram represents a molecule having a nonpolar covalent bond?

1 link  

2 of the same element bonded= nonpolar bond

36 Which quantity is equal to 50 kilojoules?

(I ) 0.05J        (3) 5 x 103J

(2)   500J       (4) 5 x 104J

4   first replace kilo with x 103  (table C prefixes)

50 x 103 which is 5 x 104

37 Which compound is formed from its elements by an exothermic reaction at 298 K and 101.3 kPa?

(1) C2H4(g)       (2) HI(g)

(3) H2O(g)        (4) NO2(g)

3 link Table I  exothermic has a negative delta H

 

38 At which temperature is the vapor pressure of ethanol equal to 80. kPa?

(1) 48C     (3) 80. C

(2) 73C     (4) 101 C

2 link

 

Table H

39 At 25C, gas in a rigid cylinder with a movable  piston has a volume of 145 mL and a pressure of  125 kPa. Then the gas is compressed to a volume of 80. mL. What is the new pressure of the gas if the temperature is held at 25C?

(1) 69 kPa            (3) 160 kPa

(2) 93 kPa            (4) 230 kPa

4 link

 

PV=PV  (temperature is constant, so leave it out)

145ml x 125kPa= P x 80.ml

226 kPa=P

230kPa=P (sig figs)

40 A 2400.-gram sample of an aqueous solution contains 0.012 gram of NH3. What is the concentration of NH3 in the solution, expressed as parts per million?

(1) 5.0 ppm        (2) 15 ppm       (3) 20. ppm      (4) 50. ppm

1 link  

(0.012g/2400.g) x 1,000,000=5.0ppm

Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50 Questions 51-54 Questions 55-57 Questions 58-59 Questions 60-62 Questions 63-65 Questions 66-69  Questions 70-71  Questions 72-74 Questions 75-78  Questions 79-81  Questions 82-85
 
Back to Regents Exams