Here are the answers to your questions:
17. How many atoms are in the products when one molecule of Iodine (I2) and two molecules of sodium chloride (NaCl) combine?
- I2 contributes 2 iodine atoms.
- 2 NaCl contributes 2 sodium atoms and 2 chlorine atoms, which totals 4 atoms (2 Na + 2 Cl).
- Therefore, the total number of atoms in the products is 2 (from I2) + 4 (from NaCl) = 6 atoms.
- Answer: D) 6
18. Are the following examples of chemical or physical changes?
- A silver spoon tarnishing:
- A) Chemical change
- Blowing a dandelion:
- B) Physical change
- Building a sand castle:
- B) Physical change
- Toasting bread:
- A) Chemical change
19. Which statement comparing ionic and covalent bonds is correct?
- a) Covalent bonds tend to be less polar than ionic bonds. (True)
- b) Elements in Group 1A are more likely to form covalent bonds than ionic bonds with other atoms. (False - they typically form ionic bonds)
- c) More electrons are transferred from covalent bonds than ionic bonds. (False)
- d) The difference between electronegativities is greater in covalent bonds than for atoms in ionic bonds. (False)
Therefore, the correct statement is a) "Covalent bonds tend to be less polar than ionic bonds."
20. Balance the following chemical equation: _ Mg + _ F2 → _ MgF2.
- To balance the equation, you need 1 magnesium (Mg) and 2 fluorine (F) atoms for every formula unit of magnesium fluoride (MgF2). Therefore, the coefficients are:
- 1 Mg + 1 F2 → 1 MgF2
This gives a balanced equation of: 1:1:1. Answer: b) 1:1:1