August 2007 Chemistry Regents #31-40

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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

 

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Answer Explanations
31 What is the net charge on an ion that has 9 protons, 11 neutrons, and 10 electrons?
(1) 1+   (3) 1
(2) 2+   (4) 2
3 more electrons means it is negative
32 Which two particles make up most of the mass of a hydrogen-2 atom?
(1) electron and neutron
(2) electron and proton
(3) proton and neutron
(4) proton and positron
3 H-2 has a proton and a neutron
33 Which statement explains why sulfur is classified as a Group 16 element?
(1) A sulfur atom has 6 valence electrons.
(2) A sulfur atom has 16 neutrons.
(3) Sulfur is a yellow solid at STP.
(4) Sulfur reacts with most metals.
1 group 16, 6 valence electrons
34 How do the atomic radius and metallic properties of sodium compare to the atomic radius and metallic properties of phosphorus?
(1) Sodium has a larger atomic radius and is more metallic.
(2) Sodium has a larger atomic radius and is less metallic.
(3) Sodium has a smaller atomic radius and is more metallic.
(4) Sodium has a smaller atomic radius and is less metallic.
1 table S for radius

more metallic bottom left of the PT

35 A compound has a molar mass of 90. grams per mole and the empirical formula CH2O. What is the molecular formula of this compound?
(1) CH2O (3) C3H6O3
(2) C2H4O2 (4) C4H8O4
3 CH2O=30g/mol

90/30;  so 3 times this

36 At standard pressure, a certain compound has a low boiling point and is insoluble in water. At STP, this compound most likely exists as
(1) ionic crystals
(2) metallic crystals
(3) nonpolar molecules
(4) polar molecules
3 water is polar and like dissolves like, so nonpolar

low BP covalent

2 compare densities

 

mass/volume

38 Which group on the Periodic Table of the Elements contains elements that react with oxygen to form compounds with the general formula X2O?
(1) Group 1    (3) Group 14
(2) Group 2    (4) Group 18
1 X has a charge of +1

so group 1

39 An unsaturated solution is formed when 80. grams of a salt is dissolved in 100. grams of water at 40.C. This salt could be
(1) KCl       (3) NaCl
(2) KNO3   (4) NaNO3
4 Below the line on TABLE G at 40C
40 Which kelvin temperature is equal to 56C?
(1) 329 K (3) 217 K
(2) 217 K (4) 329 K
4 add 273

Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

 
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