PISA Mocktest Science 50 Items PDF

**SCIENCE** **Directions:** Read and carefully analyze each question. Write the best answer on your answer sheet. 1\. The collision of the continental South American plate and the oceanic Nazca plate gave rise to an orogeny or mountain building activity that produced the Andes Mountain, which illu...

**SCIENCE** **Directions:** Read and carefully analyze each question. Write the best answer on your answer sheet. 1\. The collision of the continental South American plate and the oceanic Nazca plate gave rise to an orogeny or mountain building activity that produced the Andes Mountain, which illustration shows the movement of the two plates?   A B C D For item 2, refer to the topic below titled "Subduction Zone". A subduction zone is the biggest crash scene on Earth. These boundaries mark the collision between two of the planet\'s tectonic plates. Where two [tectonic plates](https://www.livescience.com/37706-what-is-plate-tectonics.html) meet at a subduction zone, one bends and slides underneath the other, curving down into the mantle. Scientists first identified subduction zones in the 1960s, by locating earthquakes in the descending crust. The largest earthquakes ever recorded were on subduction zones, such as a magnitude 9.5 in Chile in 1960. Pacific Ring of Fire reveals the link between subduction zones and volcanoes. Inland of each subduction zone is a chain of spouting volcanoes called a [volcanic arc](https://www.livescience.com/22566-caribbean-arc-tectonics.html), such as Alaska\'s Aleutian Islands.   2\. Which part of the map will most likely have least occurrence of earthquakes? A. 1 B. 2 C. 3 D. 4 For item 3, refer to the selection below titled "An Earthquake that Shook the Entire World". The Great Chilean Earthquake was the strongest earthquake recorded during the twentieth century. Within minutes of the earthquake, tsunamis with waves up to 11.5 meters high rampaged the Chilean coastline and move westward from Chile through the expanse of the Pacific Ocean. Within 22 hours, the waves hit Japan. The earthquake was tectonic in origin, caused by subduction movement of the Nazca Plate beneath the South American Plate. 3\. Which of the following conclusions can be derived based from the selection? A. Tsunami hit Japan. B. Earthquakes were recorded during twentieth century. C. The shifting of the seafloor generated tsunamis. D. The Great Chilean Earthquake took many lives. For item 4, refer to the graph below. A variety of human activities can induce earthquake sequences. A breakdown of the causes and proportions documented in HiQuake is shown below.  Causes of induced seismicity 4\. What will happen if the people stop extracting Coal Bed Methane (CMB)? Short Response: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ For item 5, study the graph below on the "Causes of Induced Seismicity" : 5\. Which statement best describes the two graphs? B. Extraction of conventional oil and gas has the least number of earthquake cases. D. Frackling activities contribute the most induced seismicity but least intensity. A. **BOLP** B. PALP C. BALP D. All three seismic stations A. **The North American and Eurasian plates are drifting away from each other thus creating a rift valley.** B. **The North American and Eurasian plates are moving towards each other thus creating a rift valley** C. **The Mid-Atlantic Ridge is being pulled by North American and Eurasian Plates that caused the formation of a rift valley.** D. **The Mid-Atlantic Ridge is moving away from the boundary of North American and Eurasian Plates.** 8. **A chain of mountains is located near the coast of a continent next to a plate boundary. Which sentence describes how these mountains were most likely formed?** A. **As two continental crusts collide, mountains and earthquakes will be formed.** B. **As two oceanic plates moved apart, new seafloor was produced, forming a ridge.** C. **As a continental plate and an oceanic plate collided, part of the oceanic plate subducted, volcanoes erupted, and the crust buckled, forming the mountains.** D. **As two oceanic plates collided, one of the oceanic plates subducted, and the other plate rose to the surface, forming folded mountains.** 9. Convection at the mantle can be driven by temperature differences. How will you relate temperature differences in the movement of plates? A. Temperature differences at the mantle causes hot materials to contract and become less dense and expand and become denser when it cools down. B. Temperature differences at the mantle causes hot materials to expand and become less dense and contract and become denser when it cools down. C. Temperature differences at the mantle cause hot materials to contract and become denser and expand and become less dense when it cools down. D. Temperature differences at the mantle drive the movement of plates causing the cold and hot materials to sink. 10. What was the magnetic polarity three millions of year's age of Earth before present? A. **reversed magnetic polarity** B. normal magnetic polarity C. no reversal of earth's magnetic polarity. D. no information can be generated from the magnetic polarity map. 11. What can you say about the ages of the oceanic floor from both sides of the mid-oceanic ridge? A. The ages of the oceanic floor from both sides of the mid-oceanic ridge are not the same. B. **The ages of the oceanic floor from both sides of the mid-oceanic ridge are the same.** C. The ages of the oceanic floor from both sides are older near the ridge and younger far from it. D. The ages of the oceanic floor from both sides of the mid-oceanic ridge cannot be determined from the map. 12. Why do magnetic patterns found on the ocean floor seem to be puzzling for our scientists? For item 13, read and analyze the situations below. **Eyeglasses** with **convex lenses** increase refraction, and accordingly reduce the focal length. Eyeglasses with concave lenses reduces the refraction of light and lengthens the focal length. Ruby sees near objects clearly but far objects blurry while Chelsea perceives near objects fuzzy but far objects clearly. When they went to Dr. Johnson, an optometrist, he prescribed the different eyeglasses. 13. Ruby will use eyeglasses with \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ lenses while Chelsea will wear eyeglasses with \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ lenses. 14. While standing on a boat, Arnold wished to catch the fish using laser gun, would he aim above, below, or directly at the observed fish to make a direct hit? Your Answer: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 15\. Based from the situation on item 14, Arnold changed his mind and wanted to use a spear instead. In order for him to catch the fish he should aim \_\_\_\_\_\_\_\_\_\_ the/at observed fish to make a direct hit. A. above B. below C. directly D. beside For item 16, refer to the figure and selection below. Induction Cooker *Some induction cookers use smart pans with built-in sensors. 1) The coil in the cooktop generates a magnetic field. 2) A piece of iron or steel embedded inside the pan picks up the field and converts it into heat. 3) A [thermocouple](https://www.explainthatstuff.com/howthermocoupleswork.html) (electrical temperature sensor) directly underneath continually monitors how hot the pan is getting. 4) A separate [induction coil](https://www.explainthatstuff.com/inductionchargers.html) inside the pan picks up energy from the cooktop and converts it into just enough electrical power to drive a small [radio](https://www.explainthatstuff.com/radio.html) transmitter. 5) The transmitter sends information from the temperature sensor back to the cooktop (6). The cooktop picks up the radio signal (7) and raises or lowers its power as necessary.* *16. Mr. Castro wants to use his newly purchased induction cooker, what type of pan will he use so that it will work properly with the induction cooker?*  Your Answer: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ For item 17, refer to the selection below. Metal Detector [Walk-through metal detectors](https://kintronics.com/solutions/ip-door-access-control/walk-metal-detectors/) typically use **pulse induction** (PI) technology. The PI systems send powerful, short bursts (pulses) of current through the coil of wire. Each pulse generates a short magnetic field. When a piece of metal passes through the magnetic field, a reflected magnetic field is created. This magnetic field then reacts with the receiver coil, which, in turn, triggers the alarm system.  17\. Which of the following is true? A. The metal detector can detect the pearl earrings of Jill. B. The metal detector can detect the bunch of candies inside the pocket of Joerge C. The metal detector can detect the diamond ring of Julia. D. The metal detector can detect the cigarette packs in the luggage of Anna. For item 18, refer to the selection and the figure below. Waves can be classified based on their capability to travel or propagate in different medium. There are waves which can travel through various materials even in vacuum or empty space, these kinds of waves are categorized as electromagnetic waves. On the other hand, waves that can propagate in other materials except in vacuum are referred as mechanical waves. Let us try to understand more of their differences in terms of their propagation and speed.  Figure: Occurrence of Lightning and Thunder The occurrence of lightning and thunder is used to further explain the two classifications of waves. During a storm, we observe that lightning comes first before the thunder. This is an example of how the two classifications of waves can be compared in terms of their speed. **18. Based on the description of the two waves, explain why lightning comes first before the thunder.** A. Light easily disperses in clouds as compared to sound, hence, light is produced first than the sound. B. Lightning produces light while thunder produces vibrations, hence light is more visible than the sound. C. Light is an electromagnetic wave while sound is a mechanical wave, hence light is faster than the sound. D. Light carries more energy than sound interfering the occurrence of thunder, hence light occurs first than sound. **19. What sound explanation can you give to a person who doesn't know the negative side effect of frequent exposure to X- rays?** A. Too much exposure to X- rays damages the skin and bones of a person. B. Excessive exposure to X-rays can damage body tissues and can cause cancer. C. X-rays are very dangerous because it can penetrate and kill even the healthy cells. D. X-ray tests are expensive, and overexposure may cause impotence and other disorders. **For item 20: Three students gave a description of how electromagnetic waves are produced.** Diagram Description automatically generated Figure : Electromagnetic Waves Comics **20. Who among the student/s gave a correct statement/s?** A. Charles only B. Mary and Hanna only C. Charles and Mary only D. Charles, Mary, and Hanna For item 21-22, refer to the figure below on the Electromagnetic Spectrum. There are 7 electromagnetic waves which are specifically arranged in electromagnetic spectrum.  Figure : The Electromagnetic Spectrum **21. Which of the statements below describes the relationship between wavelength and frequency in terms of the arrangement of the 7 EM waves?** A. As wavelength decreases in one direction, the frequency also decreases. B. As wavelength decreases in one direction, the frequency increases. C. As wavelength increases in one direction, the frequency increases. D. As wavelength increases in one direction, the frequency remains. **22. Which shows a correct arrangement of the given electromagnetic waves in terms of increasing frequency?** A. Radio wave -- Infrared -- Ultraviolet Light -- Microwave -- Gamma Ray B. Infrared -- Gamma ray -- Microwave -- Radio wave -- Visible Light C. X -- ray -- Ultraviolet Light -- Visible Light -- Microwave -- Radio wave D. Microwave -- Infrared -- Ultraviolet Light -- X -- ray -- Gamma Ray **23. An image of a fetus can also be captured using higher frequency X-rays. However, pregnant women are always advised by their doctors to avoid having X-rays especially on the abdomen.** **Why is it necessary for pregnant women to avoid being X-rayed during the whole period of their pregnancy? If you are a doctor, how are you going to explain this to a patient?** **\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_** **\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_** **\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_** **24. Who tells the correct information about concave mirror?** +-----------------------+-----------------------+-----------------------+ | **MARIA says...** |  | | | | **RYAN says...** | | +=======================+=======================+=======================+ | **"concave mirror | **"in a concave | **"** **in a concave | | will never form a | mirror, an inverted | mirror, an object can | | real image."** | image will be** | be magnified if | | | | placed at focal | | | **formed if the | point."** | | | object distance is** | | | | | | | | **greater than the | | | | focal** | | | | | | | | **length."** | | +-----------------------+-----------------------+-----------------------+ A. Maria only B. Ryan only C. Maria and Ryan, but not Ben D. Maria, Ryan, and Ben **25. Your teacher have asked you to construct a simple electric motor and this how it looked like:** **Figure : Simple Electric Motor** {#figure-simple-electric-motor.ListParagraph} ================================== **Based on its structure, what will be your indication that there is an induced current?** **A. When the wires connected to the dry cell are removed.** B. **When the magnet resting on the dry cell moves.** C. **When the coil loosens up from the loop.** D. **When the coil of wire moves or turns.** **For item 26, refer to the selection below on DNA Profiling.** DNA profiling is the process where a specific DNA pattern, called a profile, is obtain from a person or sample of bodily tissue. **It** is a forensic technique in criminal investigations, comparing criminal suspects\' profiles to **DNA** evidence to assess the likelihood of their involvement in the crime. It is use to help confirm whether two people are related to one another and is commonly used to provide evidence that someone is, or is not, the biological parent of a child. In order to confirm the person, his/her sample should be a complete match with the DNA sample taken from the crime scene/ other person. 26\. On a silent night, a loud shout from a woman was heard around the village. Police came to the house of Ms. Ann to confirm what happen. They found her lying on the floor with a knife stab on her chest. Upon investigation, three men were investigated. Below was the result of their DNA profiling. Who was the suspect/s?  A. Suspect 1 B. Suspect 2 C. Suspect 3 D. Suspects 1 & 3 27\. This is a result of DNA profiling of a family. Interpret the data and fill your answer to complete the result. Child \_\_\_\_ is the child of Mom but not Dad; Child \_\_\_\_\_\_ is not the child of Dad and Mom; while Child \_\_\_\_\_ and Child \_\_\_\_\_\_ are the children of both Mom and Dad. 28\. Scientists discovered fossils of Homo erectus in many places on Earth. In one site in Spain, scientists were puzzled by a set of events. They found the remains of ancient brush fires on top of a cliff. At the base of the cliff, they uncovered the bones of an entire herd of elephants. Scattered among the elephant bones were some stone tools. Suggest a hypothesis that would explain the events. \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 29\. What conclusion can be derived from the graph below? A. The main drivers of biodiversity decline continue to be the loss of natural habitat. B. Exploitation and climate change have a little impact to the population of species. C. Populations of mammals and fishes are the same. D. Pollution is the main cause of the reptiles and amphibians' population reduction. 30\. Which among the statements uses the result of the data? A. Crafting of guidelines about the handling of animals were done. B. The lawmakers banned the use of plastics. C. Many animal centers were created for household pets. D. The government strictly implemented the law regarding the mistreatment of animals and destruction of environment. 31\. Which is the correct sequence of the menstrual cycle? i. Egg is released from the ovary and travels through the uterus via the oviduct. The uterus continues to thicken. ii. Egg matures as estrogen is given off by the ovary. Uterus thickens. iii. The pituitary gland releases hormones that travel along a pathway. iv. If no sperm enters, the egg is not fertilized and menstruation occurs. v. When sperm enters the egg is fertilized and no menstrual cycle will happen for nine months. A. i,ii,iii,iv,v B) iii,ii,i,iv,v C) v,iv,iii,ii,i D) ii,iii,i,iv,v 32\. The *Central Dogma of Molecular Biology* states that **DNA makes RNA makes proteins** (Figure). The Central Dogma of Molecular Biology: DNA makes RNA makes proteins Figure : \| The Central Dogma of Molecular Biology: DNA makes RNA makes proteins The process by which DNA is copied to RNA is called [transcription](https://www.atdbio.com/content/14/Transcription-Translation-and-Replication#Transcription), and that by which RNA is used to produce proteins is called [translation](https://www.atdbio.com/content/14/Transcription-Translation-and-Replication#Translation). In the transcription stage, DNA and RNA undergoes several processes. Which is the correct sequence of the genetic transcription? i. Enzyme RNA polymerase binds to a region of a gene called the promoter. ii. DNA unwinds so the enzyme can "read" the bases in one of the DNA strands. iii. RNA polymerase reads the unwound DNA and builds the mRNA molecules, using complementary base pair. iv. RNA polymerase crosses a termination sequence in the gene. A. i,ii,iii,iv B) iv,i,ii,iii C) ii,i,iii,iv D) iii,i,iv,ii 33\. Helen has type I osteogenesis imperfecta, a genetic skeletal disorder. Shown below is her DNA sequence for a portion of the coding region of the collagen type I gene, which contains the mutation responsible for her disorder. The corresponding wild-type sequence is shown also. A. Deletion B. Frameshift C. Nonsense D. Silent 34\. Change in a population of horses is shown in the graph below.  A. Predation is low and resources are high. B. The horses are no longer in competition for resources with other species. C. The horse population has reached the carrying capacity of its environment. D. Interbreeding is occurring between members of different species. *For items 35 and 36, refer to figure below, which shows an outcrop of sedimentary rock whose strata are labeled A-D.* Surface A x B C D *Figure* 35. Which stratum should contain the greatest proportion of extinct organisms? Your Answer: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 36. If ʺxʺ indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum? Your Answer: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 37\. To achieve homeostasis, the nervous and endocrine systems work with each other to maintain a normal range of \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_. I. Blood calcium level II\. Temperature of the body III\. Amount of water in the body IV\. Amount of metabolic wastes in the cell A. I only C. I, II and III B. I and II only D. I, II, III, IV 38\. What will happen to a balloon when put inside the refrigerator? A. The balloon will inflate. B. The balloon will shrink. C. The balloon will burst. D. The balloon will float. 39\. Suppose we have a theoretical gas confined in a jar with a piston at the top. With the temperature and number of moles held constant, two weights are slowly added to the top of the piston A. What will happen to the two set-ups?  A. Set-up A has greater volume that Set-up B. B. Set-up A and B have the same volume. C. Set-up A has greater pressure that Set-up B. D. Set-up B has greater pressure that Set-up A. 40\. Based from the illustration from item 39, what happens to the temperature of Set-up B if you will remove 2 weights on the piston and add it on Set-up A? A. Set-up B will have lower temperature than Set-up A. B. Set-up B will have high temperature than Set-up A. C. Set-up B will have the same temperature with Set-up A. D. Set-up B will have double its temperature compared to Set-up A. For items 41-42, refer to the selection below. One way in which humans have affected the climate is by increasing [**emissions**](http://www.cotf.edu/ete/modules/climate/GCglossary.html#emissions) of [**greenhouse gases**](http://www.cotf.edu/ete/modules/climate/GCglossary.html#greenhouse%20gases). Greenhouse gases absorb infrared (long-wave, heat) radiation. This is the form of the sun\'s energy reflected off the earth\'s surface. Greenhouse gases then radiate heat energy back toward the earth. This heats the earth\'s atmosphere and ultimately contributes to increasingly warmer climates. **Carbon dioxide** (CO~2~) is a byproduct of the combustion\--or burning\--of [**fossil fuels**](http://www.cotf.edu/ete/modules/climate/GCglossary.html#fossil%20fuels) such as coal and oil that contribute to climate change. In order to help with the problem, Allbirds, an environmentally friendly footwear company, has launched a running shoe called \'Tree Dasher\'.  It is made from natural and plant-based materials like sugarcane and eucalyptus, including the company\'s signature fiber, merino wool. Based on \'CO~2~e\' (carbon dioxide equivalent emissions) - a term that describes the amount of carbon dioxide that would have the equivalent impact on global warming - the Tree Dasher\'s emission is around 30 percent less than that of a standard sports shoe, estimated at 12.5kg. 41-42. Identify the problem and the solution from the article above. 41\. Problem: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 42. Solution: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ For item 43, refer to the graph below. What does the graph imply regarding the rate of evaporation of water, ethanol, acetone and hexane? Short Response: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 44. The diagram shows a model of a polymer being formed. What biomolecule is this? a. a lipid b. a monosaccharide c. a polysaccharide d. a protein 45. The image on the right shows one particular property of gases. Which among the statements below **BEST** describes this property? a. Gases expand when heated and contract when cooled. b. Gases are easily compressed when pressure is applied. c. Gases exert pressure in all directions on the walls of their container. d. Gases have no definite shape and volume. They follow the shape of their containers and occupy all the spaces available. a. b\. c. d. 47. The volume and temperature are linearly related for 1 mole of methane gas at a constant pressure of 1 atm. If the temperature is in Kelvin, volume and temperature are directly proportional. The line stops at 111 K because methane liquefies at this temperature; when extrapolated, it intersects the graph's origin, representing a temperature of absolute zero. Which of the following statements **BEST** describes the relationship between the volume and temperature of a given amount of gas at constant pressure? a. The volume of a given amount of gas is directly proportional to its temperature on the Kelvin scale when the pressure is held constant. b. The volume of a given amount of gas is inversely proportional to its temperature on the Kelvin scale when the pressure is held constant. c. The pressure of a given amount of gas is directly proportional to its temperature on the Kelvin scale when the volume is held constant. d. The pressure of a given amount of gas is inversely proportional to its temperature on the Kelvin scale when the volume is held constant. 48. This diagram shows the molecular structure of glucose. Simple sugars like glucose can be used to make larger organic molecules. What is this larger molecule made from simple sugars. a. amino acids c. lipids b. carbohydrates d. monosaccharides 49\. A chemical reaction occurs when some substances change chemically to other substances. Chemical reactions are represented by chemical equations. Consider a simple chemical reaction, the burning of methane. In this reaction, methane (CH~4~) combines with oxygen (O~2~) in the air and produces carbon dioxide (CO~2~) and water vapor (H~2~O). The reaction is represented by the following chemical equation: **CH~4~ + 2O~2~ → CO~2~ + 2H~2~O** This equation shows that one molecule of methane combines with two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water vapor. Therefore, we can say that: a. The equation is balanced because same number of each type of atom appears on both sides of the arrow. b. The equation is unbalanced because the number of each type of atom that appears on both sides of the arrow is not equal. c. The equation followed the Law of Conservation of Mass because it conserved a great amount of energy during the process or chemical reaction. d. The equation does not follow the Law of Conservation of Mass because the mass of matter that ends up in the products is not the same as started in the reactants. a. 2Al*(l)* + BaO*(s)* → Al~2~O~3~*(s)* + 3Ba*(l)* b. CH~4~*(g)* + 2O~2~*(g)* → CO~2~*(g)* + 2H~2~O*(g)* c. Cl~2~*(g)* + KBr*(aq)* → 2KCl*(aq)* + Br~2~*(l)* d. 2Na*(s)* + H~2~O*(l)* → 2 NaOH*(s)* + H~2~*(g)* \*\*\*END of SCIENCE TEST\*\*\*