Practice Question An atom has 14 protons and 20 neutrons. What is its atomic number?
A. 20
B. 17
C. 10
D. 14
Therefore, the Correct Answer is D.
More Questions on TEAS 7 Science
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Q #1: Nitrogen gas is an extremely stable molecule because its structure contains which of the following?
A. Resonance bonds
B. Ionic bonds
C. Triple covalent bonds
D. Hydrogen bonds
Answer Explanation
The Lewis structure of nitrogen gas is shown below. Triple bonds are stronger than double or single bonds. Therefore, we can infer that the triple bond between the two nitrogen atoms makes nitrogen gas more stable.
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Q #2: Punnett squares are used by geneticists to determine the probability of different offspring genotypes. In the one shown below, what letter(s) belong in the lower right box?
A. AA
B. Aa
C. aA
D. aa
Answer Explanation
From the given Punnett square, we can cross the genotypes of the two parents and established the phenotypes the offspring will have. The Punnett square is filled as:
A
a
a
Aa
aa
a
Aa
aa
The requested answer is aa.
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Q #3: An atom of lead (Pb) has a mass number of 207. How many neutrons are in the nucleus?
A. 130
B. 125
C. 82
D. 84
Answer Explanation
We find the number of neutrons as follows
Number of neutrons
= mass number – atomic number
= 207 – 82
= 125 neutrons
