Which formula represents a nonpolar molecule containing polar covalent bonds?

Question

H2O
CCL4 *******
NH3
H2

Can someone explain how you got the answer! plz. I know its CCL4, but how do you know its not the rest of formulas?

Piggy back this 1.

Which substance contains bonds that involved the
transfer of electrons from one atom to another?

(1) CO2 (3) KBr***
(2) NH3 (4) Cl2

Why is it KRr and not NH3...i'm sorry, i'm confused..plz explain, you might get it. thanks.

Answer 1

Baby,

I have no idea. I love you though.

Answer 2

CCl4 is a nonpolar molecule containing polar covalent bonds. A polar covalent bond exists when the difference in the electronegativity between the two atoms in the bond is greater than 0.5 - 0.7 (some people differ on the exact degree). The electrons of the bond spend more time on the more electronegative element. When the difference becomes greater than 1.5 or so, the bond is considered ionic, where there is no longer any sharing and there is true charge separation. Whether a molecule is polar or not depends on whether the vectors which make up the individual dipoles made up by the bonds cancel each other out when they are added together. This depends on the geometry of the molecule. The bonds in H2O and NH3 are polar, and due to the geometries (H2O is bent, NH3 is trigonal pyramid), the polarities of the bonds do not cancel each other out and the molecule is polar. With CCl4, being tetrahedral and with all of the polarities of the bonds being the same, adding them together does result in cancellation, making the molecule non-polar. Everything is determined by the geometry of the molecule, so it helps to either be able to picture things in 3 dimensions, or to have a molecular model kit.

Answer 3

CCl4 - the C-Cl bond is polar b/c the Cl is more electronegative than carbon, so it will have the electrons in the bond more often. Since there are four chlorines, and each are pulling in the 4 opposite directions, there is no net pull and therefore no polarization.

KBr is a salt and will dissociate upon solvation. The bond will break and both electrons will go to bromine...you'll get K+ and Br-. Similar to the way NaCl (salt) breaks up in water, going to Na+ and Br-.

Answer 4

CCl4 is completely symmetrical. It looks like C-Cl standing straight up in rthe air on a tripod of three C-Cl's. So while the C has a slight + charge, and the Cl's have slight - charges, there is no net separation of charge from one "end" of the molecule to another.

NH3 is a covalently bonded molecule. So only K+Br- fits the criterion.