1- Iron reacts with oxygen to produce iron(III) oxide. 4 Fe(s) + 3 O 2 (g) 2 Fe 2 O 3 (s) If 7.18 moles of Fe react with excess O 2 , how many moles

Iron reacts with oxygen to produce iron(III) oxide.

4 Fe(s) + 3 O2(g) → 2 Fe2O3(s)

If 7.18 moles of Fe react with excess O2, how many moles of Fe2O3 can be formed?

14.4 mol
7.18 mol
5.39 mol
3.59 mol
4.79 mol

2- Two electronic balances are tested using a standard weight. The true mass of the standard is 5.0000 g. The results of 5 individual measurements on each balance are recorded below.

Balance ABalance B 5.2895 g5.0001 g 5.1077 g4.9998 g 4.6407 g4.9999 g 4.8947 g5.0002 g 5.0672 g4.9999 g average mass =5.0000 g5.0000 g

Which statement best describes the results?

A: good precision, good accuracy. B: poor precision, good accuracy.
A: good precision, poor accuracy. B: poor precision, good accuracy.
A: good precision, good accuracy. B: good precision, poor accuracy.
A: poor precision, good accuracy. B: good precision, poor accuracy.
A: poor precision, good accuracy. B: good precision, good accuracy.

3- What is the correct formula for an ionic compound that contains magnesium ions and phosphide ions?

MgP2
Mg3P2
Mg2P3
MgP
Mg3(PO4)2

4- Which of the following statements is/are CORRECT according to valence bond theory?

1.The overlap between an s orbital and a p orbital is called a pi-bond. 2.The overlap of two s orbitals in H2 is called a sigma bond. 3.HF is formed from the overlap of a hydrogen 1s orbital with a fluorine 2p orbital.

1 only
3 only
2 and 3
1, 2, and 3
2 only