Which pair of elements would form a nonpolar covalent bond? a. bismuth and sulfurb. carbon and oxygenc. nitrogen and oxygend. silicon and phosphoro

Answer is: D.silicon and phosphorus.

When the electronegativity difference is greater, the bond polarity is increasing..  

Electronegativity (χ) is a property that describes the tendency of an atom to attract a shared pair of electrons.  

Atoms with higher electronegativity attracts more electrons towards it, electrons are closer to that atom.  

A) Δχ(Bi-S) = 2.5 - 2.0 = 0.5; polar covalent.

B) Δχ(C-O) = 3.5 - 2.5 = 1.0; polar covalent.

C) Δχ(N-O) = 3.5 - 3 = 0.5; polar covalent.

D) Δχ(Si-P) = 2.2 - 1.9= 0.3; nonpolar covalent.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol