Question

1. which of the following pairs correctly matches a compound with its molecular geometry? select two correct answers. a. hydrochloric acid (hcl): trigonal planar b. water (h₂o): trigonal planar c. carbon dioxide (co₂): tetrahedral d. methane (ch₄): tetrahedral e. carbon tetrachloride (ccl₄): tetrahedral ionic compounds, such as nacl, commonly form cubic lattice structures in their solid, crystal form. which property is primarily responsible for these formations? a. covalent bonds form between the atoms in such a way as to allow the maximum sharing of electrons between the atoms. b. ionic bonds form between common positively and negatively charged ions in such a way as to keep like - charged ions far apart and oppositely charged ions close together. c. ionic bonds always result in 90 degree bond angles. d. inorganic crystals always have stronger bonds than organic crystals, resulting in square - like arrangements of atoms in the crystal lattice.

Explanation:

First Sub - Question (Matching Compounds and Molecular Geometry)

Step 1: Analyze Option A

Hydrochloric acid (HCl) is a diatomic molecule (H - Cl). The molecular geometry of a diatomic molecule is linear, not trigonal planar. So, option A is incorrect.

Step 2: Analyze Option B

Water ($H_2O$) has a central oxygen atom with two bonding pairs and two lone pairs of electrons. According to the VSEPR theory, its molecular geometry is bent (angular), not trigonal planar. So, option B is incorrect.

Step 3: Analyze Option C

Carbon dioxide ($CO_2$) has a central carbon atom with two double bonds to oxygen atoms. The molecular geometry is linear (since there are no lone pairs on the central carbon atom and the bond angle is 180°), not tetrahedral. So, option C is incorrect.

Step 4: Analyze Option D

Methane ($CH_4$) has a central carbon atom bonded to four hydrogen atoms. The carbon atom has four bonding pairs and no lone pairs. According to VSEPR theory, the molecular geometry is tetrahedral. So, option D is correct.

Step 5: Analyze Option E

Carbon tetrachloride ($CCl_4$) has a central carbon atom bonded to four chlorine atoms. The carbon atom has four bonding pairs and no lone pairs. The molecular geometry is tetrahedral. So, option E is correct.

Step 1: Analyze Option A

Ionic compounds are held together by ionic bonds, not covalent bonds. Covalent bonds involve sharing of electrons, which is not the case in ionic compounds. So, option A is incorrect.

Step 2: Analyze Option B

Ionic bonds are formed between positively and negatively charged ions. In an ionic crystal lattice, like - charged ions repel each other and opposite - charged ions attract each other. This causes the ions to arrange themselves in a way that keeps like - charged ions far apart and opposite - charged ions close together, which is responsible for the cubic lattice structures (e.g., NaCl has a face - centered cubic lattice). So, option B is correct.

Step 3: Analyze Option C

Ionic bonds do not always result in 90 - degree bond angles. The bond angles in ionic lattices depend on the arrangement of ions, and different ionic compounds can have different bond angles. For example, in some ionic compounds with more complex structures, the bond angles are not 90°. So, option C is incorrect.

Step 4: Analyze Option D

The statement that inorganic crystals always have stronger bonds than organic crystals is not true. Also, the strength of bonds is not the primary reason for the cubic lattice structure of ionic compounds. The arrangement of ions due to electrostatic forces (attraction between opposite charges and repulsion between like charges) is the main factor. So, option D is incorrect.

Answer:

D. methane ($CH_4$): tetrahedral
E. carbon tetrachloride ($CCl_4$): tetrahedral

Second Sub - Question (Property Responsible for Ionic Crystal Lattice)