SCIENCE CONTEST – STEM 2023
Time: 90 min
SECTION 1: RAIN ON EARTH.
The continuous water cycle on the earth involves rain. At the beginning of the cycle,
sunlight warms the water on earth's surface. The heat causes the water to evaporate or
change into water vapour. Water vapour is pervasive in the air. When it cools, the water
vapour returns to droplets of water.
These droplets combine to form clouds in large numbers. Smaller water droplets in a cloud
mix to form larger drops of liquid. The drips eventually weigh too much to remain in the
cloud. They descend to earth as rain and the water cycle starts over.
remain in the cloud. They descend to earth as rain and the water cycle starts over.
Question 1: How many phase trasition are there in the water cycle on the earth?
A. 2
B. 3
C. 4
D. 1
Question 2: How many states of matter are there that exist naturally on earth?
A. 3
B. 2
C. 1
D. 4
Question 3: The transition from solid to liquid is called:
A. fusion.
B. solidification.
C. vaporisation.
D. sublimation.
Question 4: Which of these following conditions would cause water to freeze (under
atmospheric pressure)?
A. Temperature reaches 100oC.
B. Temperature is under 32oF.
C. Temperature reaches 373K.
D. Temperature is exacly 293K.
Question 5: Which of the following causes the evaporation of water?
A. The sun.
B. The earth.
C. The moon.
D. The star.
Question 6: Which of these following forces is the cause for precipitation?
A. Gravitational force.
B. Electromagnetic force.
C. Elastic force.
D. Friction force.
Question 7: Rainfall is measured in mm. What does the mm refer to?
A. It should rather be measured in .
B. The volume of rainfall.
C. The average size of raindrops.
D. The height to which the collected water rise.
Question 8: In the 2008 Hanoi flood, the rainfall from October 30 to November 1 was
476.1 mm. The area of Hanoi city was 921.8 km2 back then. Estimate the volume of
rainfall in Hanoi in this historical flood.
A. 0,44 km3.
B. 1,93 km3.
C. 0,55 km3.
D. 6,41 km3.
Question 9: Researchers have calculated that the average white fluffy cloud weighs
around 500 tons. Calculate the gravitational force that the Earth is pulling the cloud
downward.
A. 5000000 N.
B. 5000 N.
C. 500000 N.
D. 500 N.
SECTION 2: SOUND WAVE
The sound wave is transported from one location to another by means of particle-to-particle
interaction. If the sound wave is moving through air, then as one air particle is displaced
from its equilibrium position, it exerts a push or pull on its nearest neighbors, causing them
to be displaced from their equilibrium position. This particle interaction continues
throughout the entire medium, with each particle interacting and causing a disturbance of
its nearest neighbors. Therefore, a sound wave is characterized as a mechanical wave.
Some animals use the reflection of sound wave to find their way and their food in the dark,
which is called “echolocation process”. Humans also use this method for submarines as
well as to find the depth of the oceans.
Question 10: What role does the outer ear play in human hearing?
A. Sound wave pickup and sound wave direction
B. Processing of sound wave stimuli
C. Acquiring information about the movement of the body in space
D. Transmit sound waves to the brain
Question 11: In which of these places could you NOT hear sound?
A. Inside the house.
B. Underwater.
C. Inside the airplane.
D. In space.
Question 12: What scale is used to measure the loudness of sound?
A. Fahrenheit scale
B. Decibel scale
C. Musical scale
D. Celsius scale
Question 13: When a sound is louder what measurement gets bigger?
A. Frequency
B. Amplitude
C. Wavelength
D. Crest
Question 14: Sound is a form of _________________ that travels as waves through a
________________.
A.light/ transparency
B. energy/ vibration
C. energy/ medium
D. frequency/ medium
Question 15: The diagram shows a cartoon of a sound wave produced while a student
is speaking.
What happens to the sound wave when the student speaks louder?
A. The amplitude increases
B. the wavelength will double
C. the speed will increase
D. the amplitude will decrease
Question 16: The students in the diagram are communicating with the cans and
string.
Which is the most likely explanation of how the students can hear and communicate
using the objects?
A. A Mechanical Wave transfers sound through the string
B. sound bounces off the can and echoes
C. sound travels through the string as an electromagnetic wave
D. Transverse wave transfers sound through ropea
Question 17: The diagram shows a research vessel using sonar to map the ocean floor.
Upon which basic behavior of sound waves does this technology depend?
A. absorption.
B. compression.
C. reflection.
D. refraction.
Question 18. A submarine, staying still, emits ultrasonic pulses to detect obstacles. The
echo returns from a cliff 2.48 s later. If the speed of sound in salt water is 1531 m/s, how
far away is the cliff?
A. About 1900 m.
B. About 3800 m.
C. About 620 m.
D. About 310 m.
Question 19. Two submarines A and B are traveling directly toward each other in still
water at speeds 9 m/s and 4 m/s. In order to detect the presence of obstacles, submarine A
emits ultrasonic waves, and detects the reflection after 0.895 second. The speed of sound
in salt water is 1531 m/s. Work out the initial distance between those 2 submarines.
A. About 691 meters.
B. About 685 meters.
C. About 1370 meters.
D. About 1382 meters.
Question 20. The buzzing sound of the fly is a result of the beating of its two wings. A
housefly’s wing beats about 15000 times per minute, what is the frequency of its
noise?
A. 900 000 Hz
B. 15 000 Hz
C. 15 060 Hz
D. 250 Hz
SECTION 3: THE ECOSYSTEM
An ecosystem is a geographic area where plants, animals, and other organisms, as well as
weather and landscape, work together to form a bubble of life. Ecosystems contain biotic
or living, parts, as well as abiotic factors, or nonliving parts. Biotic factors include plants,
animals, and other organisms. Abiotic factors include rocks, temperature, and humidity.
Ecosystem depends on every other factor, either directly or indirectly. A change in the
temperature of an ecosystem will often affect what plants will grow there, for instance.
Animals that depend on plants for food and shelter will have to adapt to the changes, move
to another ecosystem, or perish. Ecosystems can be very large or very small. Tide pools,
the ponds left by the ocean as the tide goes out, are complete, tiny contain seaweed, a kind
of algae, which uses photosynthesis to create food. Herbivores such as abalone eat the
seaweed. Carnivores such as sea stars eat other animals in the tide pool, such as clams or
mussels.
Question 21: A sequence of organisms that are nutritionally related to each other, in
which one species feeds on another in front and is the food on the next.
A. food web
B. trophic level
C. food chain
D. link
Question 22: Choose the correct statement from the following statements
A. The plant lives in wet but well-lit places such as lakes and ponds with narrow leaf blades
and underdeveloped hedges.
B. Plants that live in arid places or have succulent bodies, or reduced leaves and stems,
leaves turning into spines.
C. Reptiles are less resistant to dehydration than frogs.
D. Reptiles are poorly adapted to the arid environment of the desert.
Question 23: Which of the following forms of biodiversity describes all of the different
livable spaces in an ecosystem?
A. Species
B. Habitat
C. Genetic
D. None of the Above
Question 24: Which do you think has a higher species diversity, a food chain or a food
web?
A. Food Chain
B. Food Web
C. Similar
D. Can not be compared.
Question 25: This diagram provides information on the diversity, in number of
species, for four major groups of animals over time. What is the only group that
experienced an increase of diversity between 413 million years ago and 265 million
years ago?
A. Mollusks
B. Echinoderms
C. Arthropods
D. Chordates
Question 26: What animal is on the top of the food chain?
A.Grass
B. Grasshopper
C. Mouse
D. Owl
Question 27: Where does the energy start in this food chain?
A. Plant
B. Sun
C. Deer
D. Wolf
Question 28: Which of these organisms would receive energy from the snake?
A. Plant
B. Rabbit
C. Mouse
D. Hawk
Question 29: Which of these is true about this food web?
A. The Owl gets its energy from the producer.
B. The Lion gets its energy only from a wild cat.
C. The Kite gets its energy from the goat.
D. The Mouse is most likely to die, several ways.
Question 30: One of the longest living animals is turtle. Which category of animal is
a turtle?
A. Reptiles.
B. Amphibians.
C. Birds.
D. Mammals.
SECTION 4: ENERGY FROM THE SUN
Solar power is energy from the sun. The sun has been producing energy for billions of
years, but it is only in the recent past years that this energy is collected and changed into
heat and electricity. The energy from the rays of the sun is called solar radiation. The energy
from the sun has given power to all living things through photosynthesis. Photosynthesis
takes place when plants use the sun’s energy to make its own food, and then of course, all
other living organisms eat the plants or animals receiving that energy indirectly from the
sun.
Photosynthesis is the process in which light energy is converted to chemical energy in the
form of sugars. In a process driven by light energy, glucose molecules (or other sugars) are
constructed from water and carbon dioxide, and oxygen is released as a byproduct. The
glucose molecules provide organisms with two crucial resources: energy and fixedorganic-carbon.
Question 31: According to the diagram, solar panel can convert solar energy into
A. electrical energy.
B. mechanical energy.
C. thermal energy.
D. gravitational energy.
Question 32: Which of these following is not renewable energy resource?
A. Fossil fuels.
B. Solar power.
C. Geothermal power.
D. Wind power.
Question 33: The kinetic energy of air passing through a wind turbine every minute
is 720 000 J. In one hour, the amount of electrical energy generated from the turbine
is 7776000 J. Calculate the efficiency (%) of the wind turbine.
A. 18%
B. 9,26%
C. 55,99%
D. 82%
Question 34: Each group of solar cells is arranged in a rectangle 1.2 m × 2.8 m. The
solar cells are situated in a region where 260W of solar energy is received per square
meter of the cells. The electrical power output of each group of solar cells is 215W.
Calculate the efficiency of the solar cells.
A. 24.6%
B. 82,7%
C. 17,3%
D. 75,4%
Q4. In order to incentivize electricity saving, the national electricity company of
Vietnam (EVN) provides pricing by “step”: the rate changes with the amount of use.
Here are the details:
Step 1: 0-50kWh: 1678 VNĐ/kWh
Step 2: 51-100kWh: 1734 VNĐ/kWh
Step 3: 101-200kWh: 2014 VNĐ/kWh
Step 4: 201-300kWh: 2536 VNĐ/kWh
Step 5: 301-400kWh: 2834 VNĐ/kWh
Step 6: From 401kWh: 2927 VNĐ/kWh
If Mrs. Linh paid 368 000 VNĐ for her energy bill in February 2023, how much
electricity did she use in that month (in kWh)?
A. 277 kWh
B. 194 kWh
C. 387 kWh
D. 242 kWh
Question 35:What are the raw materials of photosynthesis?
A. oxygen and carbon dioxide
B. oxygen and glucose
C. carbon dioxide and water
D. water and glucose
Question 36: What is the food that plants make called?
A. glucose
B. oxygen
C. leaves
D. carbon dioxide
Question 37: What is the chemical formula for carbon dioxide?
A. H2O
B. CO2
C. CHO2
D. CO2H
Question 38: Why are plants usually green?
A. Because the chlorophyll reflects green light
B. Because the chlorophyll absorbs green light
C. Because the accessory pigments combine to make green
D. Because the accessory pigments only absorb green light
Question 39: Which of these conditions would decrease the rate of photosynthesis in
a plant?
A. Above average precipitation
B. Changing the daylight hours from 14 hrs to 10 hrs
C. Changing the CO2 concentration from 380 ppm to 410 ppm
D. All of these choices
Question 40: A student is collecting the gas given off from a plant in bright sunlight
at a temperature of 27°C. The gas being collected is probably ________.
A. oxygen
B. carbon dioxide
C. ATP
D. glucose
Question 41: If we enclosed a plant in an air-proof bottle, what would happen to the
rate of photosynthesis
A. Gradually slow down to zero because CO2 is used up
B. Shows a constant rate as long as the light remains on
C. Gradually speeds up because O2 builds up
D. Gradually slows down because glucose builds up
Question 42: If carbon dioxide is completely removed from a plant’s environment,
what would you expect to happen to the plant’s production of high-energy sugars
(rate of photosynthesis)?
A. Sugar production will likely increase.
B. Sugars will not be produced.
C. The rate of sugar production will decrease .
D. Fewer sugars will be produced at first, but then the plant will recover
SECTION 5: CORONA VIRUS
In social networks and even mentioned by an American congressman a 'conspiracy theory'
that the virus causing the COVID-19 epidemic is a biological weapon created by a
laboratory in Wuhan, and for some reason being ' freed the barn'! A team of 27 scientists
outside China has determined that the Covid-19 virus is not man-made. Furthermore,
genetic analysis showed that the new virus (now known as SARS-Cov-2) originated from
the coronavirus found in bats, with a similarity rate of up to 96%.
This new virus has six mutations in the receptor region that help it connect to the ACE2
receptor in humans, pigs, cats, pangolins (and possibly other animals). This mutation is
more consistent with viral evolution than man-made. After entering human cells, they
begin to replicate (or continue to infiltrate other cells). To replicate, they must use 'engines'
(and this fact has implications for the therapeutics discussed below). After entering the
lungs, they attack the celia cells of the lungs (which are responsible for producing mucus
to protect the lungs).
Question 43: Corona virus is a virus transmitted from
A. Person to person.
B. Animals to humans.
C. Human to animal.
D. Animal to Animal.
Question 44: Which statement about viruses is correct?
A. The structure consists of many coordinated components.
B. The genetic material is ADN or ARN.
C. No outer shell.
D. Self-replicating when living in the environment.
Question 45: Viruses are obligate intracellular parasites because they
A. microscopic size.
B. has a prokaryotic cell structure.
C. has no cellular structure.
D. has an irregular shape.
Question 46: Cell growth is closely related to which of the following processes?
A. Metabolism, induction and reproduction.
B. Metabolism.
C. Reproduction.
D. Touch.
Question 47: Determine the structure of the virus by choosing the correct answer.
A. (1) Outer shell, (2) protein shell, (3) Core part.
B. (1) Protein shell, (2) outer shell, (3) Core part.
C. (1) Core, (2) Protein coat, (3) Outer shell.
D. (1) Outer shell, (2) Core, (3) protein coat.
Question 48: The basic reproduction number, R0, is the expected number of cases
directly generated by one case in a population where all individuals are susceptible to
infection.
Choose the right statement among the following:
A. When R0 = 0.85, the virus is spreading in the population.
B. When R0 = 0.85, the size of the infectious population will eventually reduce.
C. When R0 = 0.85, the size of the infectious population will remain unchanged.
D. R0 = 0.85 are not related to the spreading of viruses.
Question 49. The basic reproduction number is calculated using this formula R0 =
B.T, in which B is the average infection-producing contacts per unit time, and T is the
mean infectious period. Assuming that in a community, each person makes 14
contacts a day on average, and one tenth of those contacts are infectious. The mean
infectious period of coronavirus is 11 days. Calculate R0.
A. 15,4
B. 1,27
C. 14
D. 0,79
Question 50. Assuming that on April 20th 2021, there were 2 undetected infectious
cases F0. Without restriction, the virus spread with the basic reproduction number
of R0 = 22. Given that the incubation period (not transmissible) of coronavirus is 4
days, and the mean infectious period of coronavirus is 11 days, estimate the maximum
and the minimum number of infected cases on May 20th, 2021?
A. Max ≈ 227 millions; Min = 968
B. Max ≈ 114 millions; Min = 484
C. Max ≈ 4,2 millions; Min = 44
D. Max ≈ 8,4 millions; Min = 22