A rock in which water cannot easily pass through is termed

Step 1: Analyze the question The question asks for the term used for a rock that does not allow water to pass through it easily.

Step 2: Explain the concepts

• Permeable rock: has connected spaces or cracks, so water can pass through it easily. Examples are sandstone and limestone, which has joints.
• Porous rock: has pores (tiny spaces) that can hold water. Porosity is about how much water a rock can store, not how easily water moves through it. Clay is a good example: it is porous and can hold a lot of water, but its pores are so tiny and poorly connected that water barely moves through it.
• Impermeable rock: does not allow water to pass through it easily. Examples are clay, shale, slate and granite (when unjointed).
• Aquifer: a rock layer that both stores and transmits water, such as sandstone. Wells and boreholes tap into aquifers.

Step 3: Match the definition to the options

• A. Permeable: this is the opposite of what the question describes, so it is wrong.
• B. Porous: this describes a rock's ability to hold water, not to block it, so it is wrong.
• C. Impermeable: this matches the description exactly, so it is correct.
• D. Aquifer: this is a water-bearing rock, the opposite of a water-blocking one, so it is wrong.

Step 4: Answer The correct term is impermeable, which is option C.

Exam tip: Look at the prefix. "Im-" means "not," so impermeable means "not permeable." Also remember that porous is about storing water, while permeable is about letting water pass through. WAEC often tests this difference.