Question

true/false. write t if the statement is true and f if the statement is false.

1. the charges on electrons and neutrons cancel each other to give neutral atoms.
2. a cation forms when an atom gains a proton or loses an electron.
3. all carbon atoms have exactly 6 protons.

multiple choice. choose the one alternative that best completes the statement or answers the question.

1. when an atom gains an electron, the resulting particle is called

a) a cation
c) an anion
b) a proton
d) none of the above

1. what is the correct formula for a potassium ion with 18 electrons?

a) p-
b) p+
c) k-
d) k+
e) none of the above

1. cr is a member of which family?

a) noble gases
b) halogens
c) alkali metals
d) alkaline earth metals
e) none of the above

1. what is the charge on the ion formed by selenium?

a) 1+
b) 1-
c) 2-
d) 2+
e) none of the above

1. how many protons and electrons are present in o2-?

a) 16 protons and 8 electrons.
b) 8 protons and 8 electrons.
c) 10 protons and 8 electrons.
d) 8 protons and 10 electrons.
e) none of the above
f) an isotope

1. isotopes are:

a) atoms of the same element that have different number of protons.
b) atoms of the same element that have different number of neutrons.
c) atoms of the same element that have the same number of neutrons.
d) atoms of the same element that have different number of electrons.
e) none of the above

Explanation:

Step1: Analyze question 31

Electrons have a negative charge and neutrons have no charge, they don't cancel each other to give neutral atoms. So the statement is false.

Step2: Analyze question 32

A cation forms when an atom loses an electron or gains a proton. So the statement is true.

Step3: Analyze question 33

Carbon is atomic - number 6, and all carbon atoms have exactly 6 protons. So the statement is true.

Step4: Analyze question 34

When an atom gains an electron, it has a negative charge and is called an anion.

Step5: Analyze question 35

Potassium (K) has an atomic number of 19. A potassium ion with 18 electrons has lost 1 electron, so the formula is K⁺.

Step6: Analyze question 36

Chromium (Cr) is a transition - metal, not a member of noble gases, halogens, alkali metals, or alkaline earth metals.

Step7: Analyze question 37

Selenium (Se) is in group 16 of the periodic table. It gains 2 electrons to form an ion with a 2 - charge.

Step8: Analyze question 38

Oxygen (O) has an atomic number of 8, so it has 8 protons. The O²⁻ ion has gained 2 electrons, so it has 10 electrons.

Step9: Analyze question 39

Isotopes are atoms of the same element that have different numbers of neutrons.

Answer:

1. F
2. T
3. T
4. C. an anion
5. D. K⁺
6. E. none of the above
7. C. 2 -
8. D. 8 protons and 10 electrons
9. B. atoms of the same element that have different number of neutrons