January 2015 Chemistry Regents #3640
Highlight to reveal answers and explanations


Questions 
Answer  Links 
Explanations 
36 The table below gives the atomic mass and the abundance of the two
naturally occurring isotopes of chlorine.
Which numerical setup can be used to calculate the atomic mass of the element chlorine? (1) (34.97 u)(75.76) +(36.97 u)(24.24) (2) (34.97 u)(0.2424) + (36.97 u)(0.7576) (3) (34.97 u)(0.7576) + (36.97 u)(0.2424) (4) (34.97 u)(24.24) + (36.97 u)(75.76) 37 
3  Link  weighted average mass= (mass x % as a decimal) + (mass x % as a decimal) 
37 Which general trends in first ionization energy and electronegativity
values are demonstrated by Group 15 elements as they are considered in
order from top to bottom?
(1) The first ionization energy decreases and the electronegativity decreases. (2) The first ionization energy increases and the electronegativity increases. (3) The first ionization energy decreases and the electronegativity increases. (4) The first ionization energy increases and the electronegativity decreases. 
1  Link  look up the data on Table S 
38 An aluminum sample has a mass of 80.01 g and a density of 2.70 g/cm3.
According to the data, to what number of significant figures should the
calculated volume of the aluminum sample be expressed?
(1) 1 (3) 3 (2) 2 (4) 4 
3  Link  division least number of sig figs...3 


39 Given four particle models:
Which two models can be classified as elements? (1) I and II (3) II and III (2) I and IV (4) II and IV 
3  Link  must be all the same dots 
40 After being thoroughly stirred at 10.°C, which mixture is
heterogenous?
(1) 25.0 g of KCl and 100. g of H_{2}O (2) 25.0 g of KNO_{3} and 100. g of H_{2}O (3) 25.0 g of NaCl and 100. g of H_{2}O (4) 25.0 g of NaNO_{3} and 100. g of H_{2}O 
2  Link  it would have solid left so look above its line on table G 
