Final General Chemistry 1

Diamond and graphene are two carbon allotropes (they are made of only carbon atoms). Their chemical and physical properties are significantly different. It Is because of their:

• A) Different chemical composition

• B) Different chemical bond

• C) Different bond polarity

• D) Different molecular polarity

Answer explanation

graphene has double bonds

Among following molecules, please mark the ones wherein both does not obey the octet rule: CO2, H2, NO, O2

• A) CO2 and O2

• B) CO2 and H2

• C) NO and O2

• D) H2 and NO

On the basis of formal charge concept, which of following structures will be the correct Lewis structure?

• A) Lewis structure (1)

• B) Lewis structure (2)

• C) Lewis structure (3)

Answer explanation

electronegativity of N > S

order:

1. 1. formal charge = 0

2. 2. abs(formal charge) min

3. 3. the negative charge on the atom with highest electronegativity

From the following diagram, we can conclude:

• A. H-H bond length is 0.74 A

• B. H2 is in the most stable state (ground state) at H-H distance = 0.74 A

• C. H, is in the most active state at H-H distance of 0,74 A

• D. To destabilize and then eventually cut the H-H we should elongate

Which of following molecules is (are) highly soluble in water at ambient conditions room temperature and atmospheric pressure)?

• A. O2

• B. CH3CH2ОН

• C. CH3COOH

• D. CS2

Following comment could be drawn about the chemical bond angles (ONO) within the anion NO3 (nitrate)

• A) A=B>C

• B)A=B<C

• C)A= B=C

• D) A‡B=С

Which of following compounds would have largest H-X-H bond angle (X = C, N or O)?

• A) CH4

• B) NH3

• C) H2O

Answer explanation

CH4 is tetrathedral 109.5; the rest are < 109.5

Which one is more active? Polar or non polar compound?

• Polar

• Non-polar

Would either HNO2 or NO2- be expected to exhibit resonance?

• HNO2

• NO2-

• Both

• None

Answer explanation

The supposed resonance structure for HNO2 is too unstable to exist

where X is an element from the third period Na - Ar and n=1-. What is X?