The property that causes drops and streams of water to form a “skin” is called surface tension. When a group of water molecules stick together in a clump, the molecules on the outside stick even more strongly to each other. This firm bond helps individual drops of water keep their rounded shape instead of running into each other. To see surface tension in action, fill a cup with water. You can see the water form a meniscus, or rounded shape, at the top of the cup. Then carefully balance a needle flat on top of the water. The molecules at the surface of the water will have bonded together so strongly that they can support the weight of the needle without breaking.

Question

The property that causes drops and streams of water to form a “skin” is called surface tension. When a group of water molecules stick together in a clump, the molecules on the outside stick even more strongly to each other. This firm bond helps individual drops of water keep their rounded shape instead of running into each other. To see surface tension in action, fill a cup with water. You can see the water form a meniscus, or rounded shape, at the top of the cup. Then carefully balance a needle flat on top of the water. The molecules at the surface of the water will have bonded together so strongly that they can support the weight of the needle without breaking.

The “skin” in the first line of this passage is caused by

A
positively charged hydrogen atoms.

B
drops of water running into each other.

C
the extra-strong bonds between water molecules.

D
water molecules that have partially dried out and formed a crust.

Answer 1

C

the extra-strong bonds between water molecules.