General Chemistry Answers

Crystals of sodium chloride were prepared by the following method. 1 25.0 cm ^ 3 of dilute hydrochloric acid was accurately measured into a conical 2 Aqueous sodium hydroxide was added until the solution was neutral. The volume of sodium hydroxide added was measured. 3 The solution was evaporated and the crystals washed with approximately 15 cm ^ 3 of water Which row shows the pieces of apparatus used to measure the 25.0 cm ^ 2 hydrochloric acid, the volume of aqueous sodium hydroxide and the 15 cm ^ 3 of water?

9) Which of the following molecules is/are expected to be polar?

(i) CCℓ₄ (ii) SF₆ (iii) CℓF₃

A. (i) only

B. (ii) only

C. (ii) and (iii)

D. (i), (ii) and (iii)

E. (iii) only

In the following table which combination/s of electron domain geometry and molecular geometry is/are INCORRECT?

Electron domain geometry Molecular geometry

(i) IF₅ Octahedral Square pyramidal

(ii) NO₂^- Trigonal planar Trigonal planar

(iii) XeF₂ Trigonal bipyramidal linear

A. (i) only

B. (ii) only

C. (iii) only

D. (i) and (iii)

E. All are correct

Which of the following statements about the bonding in ethyne, C₂H₂, is/are INCORRECT?

(i) The s and p atomic orbitals in each carbon mix to form only one sp hybrid orbital.

(ii) The pi bonds between the two carbons are formed by the end-on overlap of the unhybridized p orbitals in each C atom.

(iii) The C−H sigma bonds each result from the overlap of the s orbital of the H and the sp hybrid orbital of C.

A. (i) only

B. (ii) only

C. (iii) only

D. (i) and (ii)

E. (i), (ii) and (iii)

8) For which one of the following molecules and ions can a valid Lewis structure NOT

 be drawn without violating the octet rule?

A. NCl₃

B. PO₄^3-

C. SF₄

D. SiCl₄

E. CO₃^2-

The bond length in an HBr molecule is 1.61 Å and the measured dipole moment is 0.44 D (a Debye = 3.34 x10^-30 C m). What is the magnitude of the negative charge on Br in the given molecule in units of e?

A. 1.6 x 10^-19

B. 9.1

C. 0.057

D. 0.22

E. 1

8) How many valence electrons are there in the NO^- ion?

A. 15

B. 14

C. 16

D. 10

E. 12

8) The electron configuration of the sulfide ion is:

A. [Ar]3s²3p⁶

 B. [Ar]3s²3p²

 C. [Ne]3s²3p⁴

 D. [Ne]3s²3p⁶

 E. [Kr]3s²3p⁶

7) Which one of the following is the CORRECT combination for the ionic compounds arranged in order of increasing lattice energy?

A. CsI < NaCl < MgO < ScN

B. NaCl < CsI < ScN < CaO

C. ScN < MgO < NaCl < CsI

D. CsI < ScN < NaCl < MgO

E. MgO < NaCl < CsI < ScN

7) Oxides of most nonmetals combine with water to form:

A. an acid

B. a base

C. water and salt

D. water

E. hydrogen gas