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Which particles are found in the nucleus of an argon atom?


NY Regents Chemistry Exam June 2019


Questions 1-10


1. Which particles are found in the nucleus of an argon atom?


(1) protons and electrons

(2) positrons and neutrons

(3) protons and neutrons

(4) positrons and electrons


Solution: Nucleus of any atom contains protons and neutrons.

Answer: 3



2 The diagram below represents a particle traveling through an electric field.

Which particle remains undeflected when passing through this electric field?


(1) proton

(2) electron

(3) neutron

(4) positron


Solution: We see positive charges on the top plane and negative charges on the bottom plane. In order to remain undeflected, the particle must have no charge.

Answer: Neutron is the only particle that has no charge out of the answer choices listed. Choice 3 is correct.


3 The mass of an electron is (1) equal to the mass of a proton (2) equal to the mass of a neutron

(3) greater than the mass of a proton

(4) less than the mass of a neutron


Solution: Electron has a very small mass (1/2000) when compared to that of proton or neutron.

Answer: Choice 4 should be the correct answer choice.



4 Compared to the energy of an electron in the second shell of an atom of sulfur, the energy of an electron in the (1) first shell is lower (2) first shell is the same

(3) third shell is lower

(4) third shell is the same


Solution: The higher the shell number of an electron, the further it is from the nucleus and the more energy it has.

Answer: 1 is correct


5 In the ground state, an atom of which element has seven valence electrons? (1) sodium

(2) phosphorus

(3) nitrogen

(4) fluorine


Solution: Number of valence electrons is equal to the group number on the Periodic Table (For groups 13-18 only count the second number). All elements in group 17 must have seven valence electrons. Fluorine is in group 17.

Answer: choice 4


6 Which information is sufficient to differentiate a sample of sodium from a sample of silver? (1) the mass of each sample (2) the volume of each sample (3) the reactivity of each sample with water

(4)the phase of each sample at room temperature


Solution: Mass, volume and phase are not unique qualities to each sample. They can be easily changed. However, reactivity with water represents chemical property of the sample.

Answer: Choice 3


7 Graphite and diamond are two forms of solid carbon at STP. These forms have (1) different molecular structures and different properties (2) different molecular structures and the same properties (3) the same molecular structures and different properties (4) the same molecular structures and the same properties


Solution: The two forms are made from the same element, carbon, but have different structures. Graphite and diamond also have different properties (graphite is soft and is used in pencils, while diamond is very hard).

Answer: Choice 1


8 As the first five elements in Group 14 are considered in order from top to bottom, there are changes in both the (1) number of valence shell electrons and number of first shell electrons (2) electronegativity values and number of first shell electrons (3) number of valence shell electrons and atomic radii (4) electronegativity values and atomic radii


Solution: Valence shell electrons are the same for the same group. Therefore, we can eliminate choices 1 and 3. Number of first shell electrons is always 2 (maximum), eliminating choice 2.Both electronegativity values and atomic radii change for group 14 elements.

Answer: Choice 4



9 Which statement explains why NaBr is classified as a compound?

(1) Na and Br are chemically combined in a fixed proportion.

(2) Na and Br are both nonmetals.

(3) NaBr is a solid at 298 K and standard pressure.

(4) NaBr dissolves in H2O at 298 K.


Solution: Compounds have atoms of elements in fixed proportions.

Answer: Choice 1



10 Which two terms represent types of chemical formulas? (1) fission and fusion (2) oxidation and reduction (3) empirical and structural (4) endothermic and exothermic


Solution: Empirical and structural are different types of chemical formula. Choice 3.

Empirical formula shows atoms of elements in their smallest whole number ratios. Structural formula shows the structure of molecule.


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