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WorksheetsWeek 20 Practice: Chemical Reactions and Energy
Total questions: 13
Worksheet time: 24mins
1-4.
Answer the questions below after watching the video
What is the primary mechanism by which an incandescent object produces light?
Electrons jumping between energy levels and releasing photons
Atoms vibrating and smashing into each other due to high heat
Chemical reactions releasing stored energy
Absorption of light and re-emission at a different wavelength
Which element is primarily responsible for producing yellow light in fireworks?
Strontium
Calcium
Sodium
Barium
How do electrons produce light in the process of luminescence?
They vibrate rapidly due to extreme heat.
They absorb light and reflect it back.
They jump to a higher energy state and then fall back, releasing a photon.
They combine with other electrons to form new light particles.
Which element was previously used to create blue fireworks but is now avoided due to its toxicity?
Copper
Strontium
Arsenic
Barium
Exothermic reactions release energy and endothermic reactions absorb energy. Is photosynthesis an exothermic or endothermic reaction?
This picture represents which of the following?
element
compound
The Sun's Electromagnetic Waves and Skin Protection
The sun emits a variety of electromagnetic waves, including visible light, infrared, and ultraviolet (UV) radiation. UV radiation is particularly important to understand because it can penetrate the skin and cause damage to cells. This type of radiation is divided into three categories: UVA, UVB, and UVC, with UVA and UVB being the most relevant to human health as they reach the Earth's surface.
Ultraviolet radiation can harm skin cells by damaging their DNA, which may lead to premature aging or even skin cancer. When UV light penetrates the skin, it can cause mutations in the DNA of skin cells, disrupting their normal function. This is why protecting the skin from excessive UV exposure is crucial for maintaining healthy skin and preventing long-term damage.
Melanin, a natural pigment found in the skin, plays a vital role in protecting against UV radiation. It absorbs UV light, preventing it from reaching and damaging the DNA within skin cells. People with higher levels of melanin tend to have darker skin, which provides more natural protection against UV rays. However, regardless of skin tone, it is important to use sunscreen and other protective measures to minimize UV exposure and safeguard skin health.
What type of electromagnetic waves emitted by the sun can penetrate the skin and cause damage to cells?
Visible light
Infrared radiation
Ultraviolet (UV) radiation
Microwave radiation
Which categories of UV radiation are most relevant to human health as they reach the Earth's surface?
UVA and UVC
UVB and UVC
UVA and UVB
UVB and infrared
What is the primary way UV radiation harms skin cells?
By causing premature aging
By damaging the DNA of skin cells
By increasing melanin production
By reducing skin elasticity
What role does melanin play in protecting the skin from UV radiation?
It reflects UV light away from the skin
It absorbs UV light to prevent DNA damage
It increases the production of skin cells
It reduces the temperature of the skin
Why is it important to use sunscreen regardless of skin tone?
To prevent skin from drying out
To minimize UV exposure and safeguard skin health
To increase melanin levels
To reduce the risk of sunburn only in lighter skin tones
When looking through a window, light is _______.
reflected
transmitted
refracted
absorbed
19.
Answer the questions below after watching the video
There were (a) oxygen atoms in the formula.
How many atoms of Carbon are in this formula? C6 H12O6
6
1
12
