Polarity

What is the shape of a molecule with four bonding pairs and zero lone pairs around a central atom?

• Tetrahedral

• Trigonal Pyramidal

• Angular

• Trigonal Planar

Answer explanation

The shape of a molecule with four bonding pairs and zero lone pairs around a central atom is tetrahedral. This is because the four bonding pairs arrange themselves symmetrically around the central atom, maximizing the distance between them and minimizing repulsion, resulting in a tetrahedral shape.

Which of the following molecules has a polar bond?

• H₂O

• N₂

• C₂H₂

• SiCl₄

Answer explanation

H₂O has a polar bond because it has a bent molecular geometry, causing an uneven distribution of electron density. Oxygen is more electronegative than hydrogen, resulting in a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. This creates a net dipole moment, making the H₂O molecule polar.

What is the shape of a molecule with two bonding pairs and two lone pairs around a central atom?

• Tetrahedral

• Trigonal Pyramidal

• Angular

• Trigonal Planar

Answer explanation

The shape of a molecule with two bonding pairs and two lone pairs around a central atom is Angular. This is because the electron pairs repel each other, causing the molecule to adopt a bent shape. Tetrahedral, Trigonal Pyramidal, and Trigonal Planar are incorrect as they do not have the same electron pair configuration.

Which of the following molecules is non-polar?

• HF

• NH₃

• HBr

• CH₃OH

Answer explanation

HBr is a non-polar molecule because it has a linear molecular geometry and the electronegativity difference between hydrogen and bromine is small. This results in a balanced distribution of electron density, making the molecule non-polar. The other options, HF, NH₃, and CH₃OH, are polar molecules due to their molecular geometries and electronegativity differences.

Is Ethanol polar or nonpolar

• nonpolar
• polar

Is Hydrogen Fluoride polar or non-polar

• nonpolar

• polar

Answer explanation

Hydrogen Fluoride is polar because it has a significant difference in electronegativity between the hydrogen and fluorine atoms. This difference leads to an uneven distribution of electron density, resulting in a dipole moment and a polar molecule.

Is Ethane polar or non-polar

• nonpolar

• polar

Answer explanation

Ethane is nonpolar because it is a symmetrical molecule with no net dipole moment. Its two carbon atoms are bonded to three hydrogen atoms each, and the C-H bonds have a relatively small difference in electronegativity. This results in a balanced distribution of electron density, making ethane a nonpolar molecule.

Is Chloroform polar or non-polar

• nonpolar

• polar

Answer explanation

Chloroform is nonpolar because it has a tetrahedral molecular geometry with three hydrogen atoms and one chlorine atom. The electronegativity difference between carbon and hydrogen is not significant enough to create a polar bond, and the symmetrical arrangement of the atoms cancels out any potential polarity, resulting in a nonpolar molecule.

Is Benzene polar or non-polar

• nonpolar

• polar

Answer explanation

Benzene is nonpolar because it has a symmetrical hexagonal ring structure with alternating single and double bonds. This arrangement leads to an equal distribution of electron density, resulting in no net dipole moment. Therefore, benzene is considered a nonpolar molecule.

What is the shape of a molecule with three bonding pairs and zero lone pairs around a central atom?

• Tetrahedral

• Trigonal Pyramidal

• Angular

• Trigonal Planar

Answer explanation

The shape of a molecule with three bonding pairs and zero lone pairs around a central atom is Trigonal Planar. This is because the three bonding pairs are distributed evenly around the central atom, forming a flat, triangular shape with bond angles of 120 degrees.