1) Which of the following statements is/are CORRECT?

1. Naturally occurring isotopes account for only a small fraction of known radioactive isotopes.
2. A few radioactive isotopes with long half-lives, such as U-235 and U-238, are found in nature.
3. Trace quantities of some short-lived radioactive isotopes, such as C-14, are found in nature because they are formed continuously by nuclear reactions.
a. 1 only
b. 2 only
c. 3 only
d. 1 and 2
e. 1, 2, and 3

Answer A

2) Ions such as [Co(H2O)6]3+ and [Ag(CN)2]– are called ____.
a. ligands
b. Lewis bases
c. chelates
d. alloys
e. coordination complexes

Answer E

3) All of the following molecules or ions can act as polydentate ligands EXCEPT ____.
a. phenanthroline; C12H8N2
b. acetylacetate ion; CH3COCHCOCH3–
c. oxalate ion; C2O42–
d. ethylenediamine; H2NCH2CH2NH2
e. dimethylamine; (CH3)2NH2

Answer E

4) What is the coordination number of the central metal ion in [Cr(en)2(OH)2]NO3? (en = H2NCH2CH2NH2)
a. 0
b. 2
c. 4
d. 6
e. 7

Answer D

5) What is the name of the compound having the formula [Cr(en)2(H2O)2]SO4?

a. dihydroxydiethlyenediamminechromate(... sulfate
b. diaquabis(ethylenediamine)sulfatochr...
c. bis(ethylenediamine)diaquachromium(I... sulfato
d. diaquabis(ethylenediamine)sulfatochr...
e. diaquabis(ethylenediamine)chromium(I... sulfate

Answer E

I disagree with 1.

I agree with 2,3,4.
I con't see all of the name typed on 5 but e is right if that is chromium IV.

To answer these questions, you need to have knowledge in chemistry. Here's how you can get the answers:

1) For the first question, read each statement carefully and determine if it is correct or not.

- Statement 1: Naturally occurring isotopes account for only a small fraction of known radioactive isotopes. This statement is incorrect because naturally occurring isotopes make up the majority of known radioactive isotopes, so it is not a small fraction.

- Statement 2: A few radioactive isotopes with long half-lives, such as U-235 and U-238, are found in nature. This statement is correct because U-235 and U-238 are indeed found in nature.

- Statement 3: Trace quantities of some short-lived radioactive isotopes, such as C-14, are found in nature because they are formed continuously by nuclear reactions. This statement is also correct because C-14 is formed continuously in the atmosphere and is present in trace quantities.

Since statements 2 and 3 are correct, the correct answer is option e) 1, 2, and 3.

2) To answer the second question, you need to know the definitions of the given terms.

- Ions such as [Co(H2O)6]3+ and [Ag(CN)2]– are called coordination complexes. This is because they involve a central metal ion (Co3+ and Ag+) surrounded by ligands (H2O and CN-) coordinated to the metal ion.

The correct answer is e) coordination complexes.

3) To answer the third question, you need to determine which molecule or ion cannot act as a polydentate ligand.

- Polydentate ligands are those ligands that can bind to the central metal ion through multiple donor atoms. Check each option to see if it fits this description.

- Option e) dimethylamine; (CH3)2NH2 does not have multiple donor atoms to bind to the central metal ion, so it cannot act as a polydentate ligand.

The correct answer is e) dimethylamine.

4) To determine the coordination number of the central metal ion in [Cr(en)2(OH)2]NO3, you need to count the number of ligands coordinated to the metal ion.

- In the compound, the ligands coordinated to the central metal ion are Cr(en)2(OH)2. The en ligand is ethylenediamine, which can coordinate through two donor atoms. There are two en ligands, so they contribute a coordination number of 4.

The correct answer is c) 4.

5) To name the compound [Cr(en)2(H2O)2]SO4, you need to identify the ligands and their coordination numbers.

- The ligands in the compound are en (ethylenediamine) and H2O (water). The coordination number is determined by the number of ligands coordinated to the metal ion, which is chromium (Cr).

- In this compound, there are two en ligands and two H2O ligands, so the coordination number is 6.

- The compound is then named as diaquabis(ethylenediamine)chromium(III) sulfate.

The correct answer is d) diaquabis(ethylenediamine)sulfatochromium(III) sulfate.