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

Therefore, the Correct Answer is B.

Q #1: Which of the following processes does atmospheric pressure play a role in?

A. Pulmonary Ventilation

B. Photosynthesis

C. Osmosis

D. Evaporation

Answer Explanation

Among the choices provided, only one process is directly influenced by atmospheric pressure:

Pulmonary Ventilation (Correct): Pulmonary ventilation, also known as breathing, is driven by pressure differences between the lungs and the atmosphere. Atmospheric pressure plays a pivotal role in this process by facilitating the movement of air into and out of the lungs.

The other options mentioned in the choices—Photosynthesis, Osmosis, and Evaporation—are not primarily influenced by atmospheric pressure. While atmospheric pressure can indirectly affect certain aspects of these processes, it is not a dominant factor in their mechanisms.
Q #2: The process that moves nutrients into the blood or lymph is

A. digestion

B. ingestion

C. elimination

D. absorption

Answer Explanation

Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma.

Ingestion is the process of taking food, drink, or another substance into the body by swallowing or absorbing it.

Elimination refers to the removal of indigestible wastes through the anus, in the form of feaces.
Q #3: Lithium has an atomic number of 3 and a mass number of 7. Which of the following is the number of neutrons in a lithium atom?

A. 4

B. 7

C. 12

D. 3

Answer Explanation

The atom is identified by the atomic number in the periodic table. The atomic number is equal to the number of protons and mass number is the sum of the number of protons and neutrons in the nucleus of an atom. Thus, to find how many neutrons are in lithium atom we use the formula below.

Mass number = number of protons + number of neutrons.

Letting n be number of neutrons in the lithium atom, we have

7=3+n

Rearranging the above equation

3+n=7

n=7-3

n=4

Thus, lithium atom has 4 neutrons.

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An atom of lead (Pb) has a mass number of 207. How many neutrons are in the nucleus?

More Questions on TEAS 7 Science

Q #1: Which of the following processes does atmospheric pressure play a role in?

Answer Explanation

Q #2: The process that moves nutrients into the blood or lymph is

Answer Explanation

Q #3: Lithium has an atomic number of 3 and a mass number of 7. Which of the following is the number of neutrons in a lithium atom?

Answer Explanation

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