January 2006 Chemistry Regents #1-10

Highlight to reveal answers and explanations

 

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

Other Regents Exams

Questions	Answer	Explanations
	3	different mass number (top) same atomic number (bottom)
2 An atom of oxygen is in an excited state. When an electron in this atom moves from the third shell to the second shell, energy is (1) emitted by the nucleus (2) emitted by the electron (3) absorbed by the nucleus (4) absorbed by the electron	2	falling electrons emit energy
3 The charge of a beryllium-9 nucleus is (1) +13      (3) +5 (2) +9        (4) +4	4	4 protons in the nucleus (atomic number)
4 Which sequence represents a correct order of historical developments leading to the modern model of the atom? (1) the atom is a hard sphere =>most of the atom is empty space=> electrons exist in orbitals outside the nucleus (2) the atom is a hard sphere => electrons exist in orbitals outside the nucleus �=> most of the atom is empty space (3) most of the atom is empty space �=>electrons exist in orbitals outside the nucleus => the atom is a hard sphere (4) most of the atom is empty space=>the atom is a hard sphere => electrons exist in orbitals outside the nucleus	1	see answer
5 Which statement describes a chemical property of oxygen? (1) Oxygen has a melting point of 55 K. (2) Oxygen can combine with a metal to produce a compound. (3) Oxygen gas is slightly soluble in water. (4) Oxygen gas can be compressed.	2	property that shows a reaction
6 The element in Group 14, Period 3 on the Periodic Table is classified as a (1) metal         (3) metalloid (2) noble gas   (4) nonmetal	3	Si, metalloid
7 Which trends are observed when the elements in Period 3 on the Periodic Table are considered in order of increasing atomic number? (1) The atomic radius decreases, and the first ionization energy generally increases. (2) The atomic radius decreases, and the first ionization energy generally decreases. (3) The atomic radius increases, and the first ionization energy generally increases. (4) The atomic radius increases, and the first ionization energy generally decreases.	1	Use Table S
8 What is the chemical formula for sodium sulfate? (1) Na2SO3    (3) NaSO3 (2) Na2SO4    (4) NaSO4	2	Na+    SO42- 2:1 ratio to balance charges
	2	count the atoms and reduce to the lowest ratio
10 Which chemical equation is correctly balanced? (1) H2(g) + O2(g)=> H2O(g) (2) N2(g) + H2(g) �=>NH3(g) (3) 2NaCl(s)=>Na(s) + Cl2(g) (4) 2KCl(s) => 2K(s) + Cl2(g)	4	same number of each atom on both sides