WAEC 2015 Geography · Question 39

The temperature at the foot of a mountain is 20oC. if the mountain is 6000 meters above sea level, what will be the temperature at the top of the mountain?

Options

A.-19.0oC
B.-16.0oC
C.14.0oC
D.19.0oC

Answer: A. -19.0oC

Explanation written with AI and checked against the answer key

Concept: Temperature falls as altitude increases. This is the normal (environmental) lapse rate, about 6.4°C per 1000 m (often rounded to 6.5°C per 1000 m). WASSCE usually uses 1°C per 150 m or 6.4°C per 1000 m. Step 1: Find the temperature drop Using 6.4°C per 1000 m: Drop = (6000 ÷ 1000) × 6.4 = 6 × 6.4 = 38.4°C Step 2: Subtract from the base temperature 20°C − 38.4°C = −18.4°C Using 6.5°C per 1000 m instead: Drop = 6 × 6.5 = 39°C Temperature = 20 − 39 = −19°C Step 3: Match with the options Option A (−19.0°C) matches the 6.5°C per 1000 m rate exactly. The 6.4 rate gives −18.4°C, which is closest to A anyway, and no other option comes near. Options C and D are positive, which is impossible for a 6000 m climb with a 20°C start. Option B (−16°C) would need a drop of 36°C, i.e. 6°C per 1000 m, which is not the standard rate. Answer: A (−19. **Tip: For lapse-rate questions, use 6.5°C per 1000 m, divide the height by 1000, multiply by 6.5, then subtract from the base temperature. Always check the sign: a high mountain with a modest starting temperature will often give a negative answer.

AI can make mistakes. Report anything that looks wrong.