Need help asap! 1. Given that the electronegativity of sulfur (S) is 2.5 and that of silicon (Si) is 1.8, which of the following best describes the chemical bonding in silicon monosulfide (SiS)?
A. ionic: transfer of electrons from silicon to sulfur
B. nonpolar covalent: equal sharing of electrons between silicon and sulfur
C. polar covalent: electrons shared between silicon and sulfur but attracted more to the sulfur
D. polar covalent: electrons shared between silicon and sulfur but attracted more to the silicon

2. Which of the following is a molecular compound?

A. Mg3N2
B. NH3
C. AlCl3
D. LiBr

3. Potassium (K) reacts with a certain nonmetallic element (Z) to form a compound with the general formula KZ; where element Z is a diatomic gas at room temperature. What is element Z?

A. Oxygen
B. Fluorine
C. Nitrogen
D. Hydrogen

1.  C. polar covalent: electrons shared between silicon and sulfur but attracted more to the sulfur

2. B)  

3. B) Fluorine

Explanation:

1. A polar covalent bond is defined as the bond which is formed when there is a difference of electronegativities between the atoms.

Electronegativity difference = electronegativity of sulphur- electronegativity of silicon = 2.5 -1.8 = 0.7

Thus as electronegativity difference is less than 1.7 , the cond is polar covalent and as electronegativity of sulphur is more , the electrons will be more towards sulphur.

2. A molecular compound is usually composed of two or more nonmetal elements. Example:

Ionic compound is formed by the transfer of electrons from metals to non metals. Example: , and

3.  For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

Here K is having an oxidation state of +1 and as the compound formed is KZ, the oxidation state of non metallic element Z should be -1. Thus the element Z is flourine which exists as diatomic gas

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g