Properties of Water

What is the shape of water molecules?

• Linear

• Tetrahedral

• Bent

• Trigonal planar

Answer explanation

The shape of a water molecule is bent. This is because water has two hydrogen atoms and one oxygen atom, and they form a bent shape to minimize repulsion. The two hydrogen atoms are not in a straight line with the oxygen atom, leading to a bent configuration. This makes 'Bent' the correct choice.

What is the charge of oxygen in a water molecule?

• Positive

• Negative

• Neutral

• Variable

Answer explanation

In a water molecule (H2O), oxygen is more electronegative than hydrogen, meaning it has a stronger pull on the shared electrons. This causes the oxygen atom to carry a partial negative charge.

What type of bonds form between water molecules?

• Covalent bonds

• Ionic bonds

• Hydrogen bonds

• Van der Waals forces

Answer explanation

Water molecules form Hydrogen bonds. This type of bond occurs when a hydrogen atom in one molecule is attracted to an electronegative atom, usually nitrogen, oxygen or fluorine, in another molecule. While Covalent and Ionic bonds are strong intramolecular bonds, they do not form between water molecules. Van der Waals forces are weaker intermolecular forces and are not as specific as Hydrogen bonds.

What property of water allows it to adhere to the xylem walls in plants?

• Adhesion

• Cohesion

• Surface tension

• Solvent power

Answer explanation

The correct answer is Adhesion. This property of water allows it to stick to the xylem walls in plants. Adhesion is the ability of water to bind to other polar compounds, including plant cell walls. This is different from cohesion, which is the ability of water molecules to stick to each other, and from surface tension or solvent power.

What property of water allows insects, like water striders, to skate on its surface?

• Adhesion

• Cohesion

• Surface tension

• Solvent power

Answer explanation

The correct answer is Cohesion. Water molecules have a property called cohesion, which is the attraction that occurs between like molecules. This property results in phenomena such as surface tension, which allows insects like water striders to skate on the water's surface without sinking.

Which type of molecules can water dissolve?

• Nonpolar molecules

• Hydrophobic molecules

• Nonionic compounds

• Polar molecules

Answer explanation

Water is a polar molecule, which means it has a slight positive charge on one side and a slight negative charge on the other. This allows it to dissolve other polar molecules. The negative end of the water molecule is attracted to the positive end of the polar molecule, and vice versa, leading to dissolution.

What happens to the density of water when it freezes?

• It increases

• It decreases

• It remains the same

• It varies

Answer explanation

When water freezes, it expands and becomes less dense, which is why ice floats on water. This is contrary to most substances, whose density usually increases as they solidify. Therefore, the density of water decreases when it freezes, which corresponds to the correct answer.

What property of water allows it to resist changes in temperature?

• Specific heat

• Heat capacity

• Thermal conductivity

• Latent heat

Answer explanation

The property of water that allows it to resist changes in temperature is its specific heat. Specific heat refers to the amount of heat per unit mass required to raise the temperature by one degree Celsius. This property makes water an excellent heat buffer, as it can absorb or release large amounts of heat with only a small change in its own temperature.

What is the term for the attraction between water molecules?

• Adhesion

• Cohesion

• Surface tension

• Solvent power

What is the effect of water temperature on its density?

• Higher temperature increases density

• Higher temperature decreases density

• Temperature has no effect on density

• Only extreme temperatures affect density

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4