Question 1:

Let's evaluate each statement to determine which one is false:

A. The nucleus of an atom contains protons and neutrons.
This is true. The nucleus is composed of protons (positively charged) and neutrons (neutral).

B. Negatively charged electrons occupy the space outside the nucleus.
This is true. Electrons are negatively charged and are found in orbitals surrounding the nucleus.

C. Atoms contain a positively charged dense nucleus.
This is true. The nucleus is small and dense, with a positive charge due to the protons.

D. The number of electrons in an atom equals the number of neutrons.
This is false. In a neutral atom, the number of electrons equals the number of protons (not neutrons). The number of neutrons can vary (isotopes) and is not necessarily equal to the number of electrons. For example, carbon-12 has 6 protons, 6 electrons, and 6 neutrons (equal in this case), but carbon-14 has 6 protons, 6 electrons, and 8 neutrons (not equal).

Thus, statement D is false.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 2:

The atomic number of an atom is defined as the number of protons in the nucleus.

Given:

• Number of electrons = 30

• Number of neutrons = 35

In a neutral atom (with no charge), the number of electrons equals the number of protons. Therefore, the number of protons is 30.

Thus, the atomic number is 30.

The options are:

• A. 30

• B. 35

• C. 65 (which is the mass number: protons + neutrons = 30 + 35 = 65)

• D. 105

Answer: A. 30

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 3:

To determine the number of protons, neutrons, and electrons in an atom of ³⁹K (potassium-39):

1. Atomic number (Z): The symbol K represents potassium, which has an atomic number of 19. This means every potassium atom has 19 protons.

2. Electrons: In a neutral atom, the number of electrons equals the number of protons. So, there are 19 electrons.

3. Mass number (A): The superscript 39 is the mass number, which is the sum of protons and neutrons. Therefore:

   Number of neutrons=A−Z=39−19=20 Number of neutrons = A − Z = 39 − 19 = 20

   So, there are 20 neutrons.

Now, match these values to the options:

• A: 19 protons, 20 neutrons, 19 electrons → Correct

• B: 19 protons, 39 neutrons, 19 electrons → Incorrect (neutrons should be 20, not 39)

• C: 20 protons, 39 neutrons, 20 electrons → Incorrect (protons should be 19, not 20)

• D: 20 protons, 19 neutrons, 20 electrons → Incorrect (protons should be 19, not 20)

Answer: A. 19 protons, 20 neutrons, 19 electrons

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 4:

To determine the correct symbol for the species with 13 protons, 14 neutrons, and 10 electrons:

Number of protons (atomic number, Z) = 13
The element with atomic number 13 is Aluminum (Al).

Number of neutrons = 14
The mass number (A) = protons + neutrons = 13 + 14 = 27.

Number of electrons = 10
Since a neutral atom of Al would have 13 electrons, having only 10 electrons indicates a charge of +3 (because it has lost 3 electrons).

Therefore, the species is Al³⁺ with mass number 27.

Now, evaluate the options:

A.
Silicon (Si) has atomic number 14 (not 13), so incorrect.

B.
This is neutral silicon with atomic number 14 and mass 27, but we need aluminum with charge, so incorrect.

C.
This has atomic number 13 (Al), mass number 27, and charge +3, which matches exactly.

D.
This has atomic number 13 (Al) but mass number 24 (should be 27) and charge +1 (should be +3), so incorrect.

The answer is C.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 6:

Let's evaluate each option for two isotopes of the same element:

Isotopes are atoms of the same element (same atomic number) that have different mass numbers due to different numbers of neutrons.

• A. They have the same number of neutrons
  This is false. Isotopes have different numbers of neutrons (by definition).

• B. They have different numbers of electrons
  This is false. In their neutral state, isotopes have the same number of electrons (since they have the same atomic number and are neutral). For example, both carbon-12 and carbon-13 have 6 electrons.

• C. They have the same chemical properties
  This is true. Chemical properties are determined by the number and arrangement of electrons. Since isotopes have the same number of electrons and the same electron configuration, they exhibit nearly identical chemical behavior. (There may be slight differences due to kinetic isotope effects, but fundamentally they are the same.)

• D. They have different atomic numbers
  This is false. Isotopes have the same atomic number (same number of protons).

Thus, the true statement is C.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 7:

To determine which species has the smallest number of neutrons, we need to calculate the number of neutrons for each option. The number of neutrons is given by:

Number of neutrons=Mass number−Atomic number Number of neutrons = Mass number − Atomic number

Let's calculate for each:

• A.  Neutrons = 198 - 78 = 120

• B.  Neutrons = 197 - 79 = 118

• C.  Neutrons = 205 - 81 = 124

• D.  Neutrons = 204 - 84 = 120

The smallest number of neutrons is 118 from option B.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 8:

To calculate the relative atomic mass of element "Z" based on the given isotopic abundances, use the formula:

Relative atomic mass=[(% abundance of isotope 1)/100 × mass of isotope 1] + [(% abundance of isotope 2)/100 × mass of isotope 2] + [(% abundance of isotope 3)/100 × mass of isotope 3]

Given:

• Isotope ⁶⁴Z: abundance = 89.43%, mass = 64

• Isotope ⁶⁴Z: abundance = 7.15%, mass = 65

• Isotope ⁶⁴Z: abundance = 3.42%, mass = 66

Now, compute step by step:

1. Contribution from ⁶⁴Z:

   89.43100/100 ×64=0.8943×64=57.2352

2. Contribution from ⁶⁵Z:

   7.15/100×65=0.0715×65=4.6475

3. Contribution from ⁶⁶Z:

   3.42/100×66=0.0342×66=2.2572

4. Sum the contributions:

   57.2352+4.6475+2.2572=64.1399

5. Round to two decimal places:
   64.1399≈64.14

Therefore, the relative atomic mass is 64.14.

Answer: D. 64.14

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 9:

Let the percentage abundance of ¹¹³In be x%. Then the percentage abundance of ¹¹⁵In is (100−x)%

The relative atomic mass is given by the weighted average:

[x⋅113+(100−x)⋅115] / 100 =114.816

Now, solve for x :

1. Multiply both sides by 100:

   x⋅113+(100−x)⋅115=11481.6

2. Expand the left side:

   113x+11500−115x=11481.6

3. Combine like terms:

   −2x+11500=11481.6

4. Subtract 11500 from both sides:

   −2x=11481.6−11500 = −18.4

5. Divide both sides by -2:

   x = 9.2

Therefore, the percentage abundance of 113In 113In is 9.2%.

Answer: C. 9.2%

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 10:

To calculate the relative atomic mass of zirconium, use the weighted average based on the isotopic abundances and masses:

Given:

• 90Zr: abundance = 51.5%, mass = 90

• 91Zr: abundance = 11.2%, mass = 91

• 92Zr: abundance = 17.1%, mass = 92

• 94Zr: abundance = 17.4%, mass = 94

• 96Zr: abundance = 2.8%, mass = 96

Now compute each contribution:

1. 90Zr
   0.515×90=46.35

2. 91Zr:
   0.112×91=10.192

3. 92Zr:
   0.171×92=15.732

4. 94Zr:
   0.174×94=16.356

5. 96Zr:
   0.028×96=2.688

Now sum these contributions:

46.35+10.192=56.542

56.542+15.732=72.274

72.274+16.356=88.63

88.63+2.688=91.318

So, the relative atomic mass is approximately 91.3.

Answer: B. 91.3

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.