June 2013 Chemistry Regents #31-40

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31 The diagram below represents the bright-line spectra of four elements and a bright-line spectrum produced by a mixture of three of these elements.

Which element is not present in the mixture?

(1) A (2) D (3) X (4) Z

 
3   line up the lines.  all the lines must be in the mixture

 

if one is missing it is out

32 What is the overall charge of an ion that has 12 protons, 10 electrons, and 14 neutrons?

(1) 2-     (3) 4­

(2) 2+    (4) 4+

2   protons are 1+

electrons are 1-

Neutrons are zero

add them up

33 As the elements in Period 3 are considered in order of increasing atomic number, there is a general decrease in

(1) atomic mass (2) atomic radius

(3) electronegativity (4) first ionization energy

2   going left to right

atomic radius decreases

See table S

 

34 Which electron configuration represents the electrons of a sulfur atom in an excited state?

(1) 2-6-6 (3) 2-8-4

(2) 2-7-7 (4) 2-8-6

2   must have 16 electrons

NOT 2-8-6 that is the ground state configuration

35 Given the word equation:

sodium chlorate ==> sodium chloride + oxygen

Which type of chemical reaction is represented by this equation?

(1) double replacement (3) decomposition

(2) single replacement (4) synthesis

3   decompositions

AX--> A + X

 

one reactant

36 Which compound has the highest percent com­position by mass of strontium?

(1) SrC12 (2) SrI2 (3) SrO  (4) SrS

3   Since they all have 1 Sr,

the highest percent is the compound that has the smallest formula mass

 

37 Given the formula for hydrazine:

How many pairs of electrons are shared between the two nitrogen atoms?

(1) 1    (3) 3

(2) 2    (4) 4

1   1 bond is 2 electrons

or 1 PAIR of electrons

38 Which formulas represent one ionic compound and one molecular compound?

(1) N2 and SO2  (2) Cl2 and H2S

(3) BaCl2 and N2O4(4) NaOH and BaSO4

3   molecular is covalent

 

2 or more nonmetals atoms bonded

 

39 Which Kelvin temperature is equal to 200.oC?

(1) -73 K   (2) 73 K (3) 200. K (4) 473 K

4   C=K-273

Back page of RT

A 10.0-gram sample of H2O(l) at 23.0°C absorbs 209 joules of heat. What is the final temperature of the H2O(l) sample?

(1) 5.0°C (3) 28.0°C

(2) 18.0°C (4) 50.0°C

3   Q=mCDT

DT=mC/Q=10g(4.18)/209J= 5°C

it was at 23, so add 5 to that because it absorbed energy

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Question 51-53 Questions 54-56 Questions 57-59 Questions 60-62 Questions 63-65 Questions 66-69 Questions 70-73 Questions 74-77  Questions 78-80  Questions 81-82  Questions 83-85

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