Four molecules each consist of a central atom with other atoms around it. in each of the molecules, the atoms surrounding the central atom are all of the same element but are different than the central atom. each of the four molecules has a different shape. which shape produces a polar molecule?
a. linear
b. trigonal planar
c. bent
d. tetrahedral

C. Bent

Explanation:

Only a bent molecule is polar.

The two bond dipoles do not cancel, so the molecule is polar.

A is wrong. In a linear molecule, the bond dipoles are equal and in opposite directions, so they cancel. The bonds are polar, but the molecule is nonpolar.

B is wrong. In a trigonal planar molecule like that shown below, the resultant of the bond dipoles of the two lower bonds is equal to the upper bond dipole and in the opposite direction. The two dipoles cancel, so the molecule is nonpolar.

D is wrong. A tetrahedral molecule may have polar bonds, but it is a nonpolar molecule. The two bonds on the right have a net dipole to the left, and the two bonds on the left have an equal resultant to the right. The dipoles cancel, so the molecule is nonpolar.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.