WAEC GEOGRAPHY PART 3 ANSWERS 2020
*Q6C. The margical material*
The magic material for overcoming the PCM problem was sugar alcohol, a common and abundantly available waste product of the food industry. Also known as molecular alloys based on sugar alcohols (MASA),
this material allows for the adjustment of the melting point and, as a result, significantly increases energy density. According to a recent article on the project published in ‘The Journal of Physical Chemistry’, sugar alcohols, when mixed with carbon nanotubes, create a material capable of storing renewable energy as heat.
The project focused on sugar alcohols as they permit high levels of undercooling, which minimises the risk of spontaneous PCM solidification.
They also reduce the requirements for insulation, as well as thermal loss during long-term storage. With the application of a local thermal shock or ultrasound, nucleation and subsequent crystallisation is induced, allowing for an easy and efficient discharge of the energy from the storage system.
*Laying the foundation*
When carbon nanotubes of varying sizes are mixed with two types of sugar alcohols – erythritol and xylitol – researchers found that, with one exception,
heat transfer within a mixture would decrease as the nanotube diameter decreased. They also found that, as a general rule, higher density combinations meant better heat transfer.
These findings are significant as they lay the foundation for the future design of sugar alcohol-based energy storage systems
*No7d*
The characteristics of hot deserts include
high temperatures in summer;
greater evaporation
than precipitation,
usually exacerbated
by high temperatures, strong wind
s and Lack of cloud cover; considerable variation in the occurrence of precipitation, its intensity and distribution; and low humidity.
*(Number 3)*
(3a)
*(Choose Any five)*
(i)Latitude
(ii)Altitude
(iii)Continentality or distance from the sea
(iv)ocean currents
(v)planetary winds and pressure belts
(v)slope and aspect
(3b)
(i)It has constant high temperature with daily temperature of 26°C with no winter
(ii)It has annual rainfall of over 200cm and rainfall is throughout the year
(iii)It has high humidity all year round with double maxima of rainfall
(iv)It has small annual temperature range of 2°C – 3°C
(v)It has convectional rainfall accompanied by lightening and thunder.
4c
Exfoliation is a process in which large flat or curved sheets of rock fracture and are detached from the outcrop due to pressure release:
As erosion removes the overburden from a rock that formed at high pressure deep in the Earth´s crust, it allows the rock to expand, thus resulting in cracks and fractures along sheet …
*8a* Air pollution occurs when harmful or excessive quantities of substances are introduced into Earth’s atmosphere.
(4a)
Weathering is defined as the gradual breaking down or disintegration of rocks by either physical or chemical process
(4b)
(i) Climate :Climate elements like temperature and rainfall are the major factors affecting Weathering. While physical Weathering is aided by temperature and water to break down rocks, chemical Weathering is aided by water and other gases in the atmosphere
(ii)Type of rocks : rocks are made up of different minerals while some are resistant to weathering others are not simply because of their differences in structure, composition and sizes of the rocks
(iii) Relief: very steep slopes like high mountains and courage weathering especially Frost action why gentle and even slopes favour chemical Weathering
(4c)
Exfoliation is a process in which large flat or curved sheets of rock fracture and are detached from the outcrop due to pressure release:
As erosion removes the overburden from a rock that formed at high pressure deep in the Earth´s crust, it allows the rock to expand, thus resulting in cracks and fractures along sheet.
3a,
-Latitude
-Topography
-ocean current
-Vegetation
-Vegetation
-Prevailing winds
(8b)
(i)Mobile source
(ii)Area sources
(iii)Natural sources
(iv)Stationary sources
(8c)
(i)Deterioration of fields
(ii)Acid rain and Smog effect
(iii)Respiratory health problems
(iv)Climate change
+++++++++++++++++++++++++++++++++
*2bi)* Divergent Bar graphs are used to compare things between different groups or to track changes over time.
*2bii)* Divergent bar graph can also be used to simply separate the marks for two dimension members, to represent a goal, or – as often seen with survey data – to show the break between desired and undesired responses.
