1. Which of the following is true about photosynthesis?
A) It is an exothermic reaction.
B) It is an endothermic reaction.**
C) It produces carbon dioxide.
D) It occurs in animals.
2. Atomic theory is
A) subject to change if new information is discovered. **
B) a solution to the problem of diering isotopes. C) unchangeable.
D) a descriptive table that lists all of the elements.
3. Two nonmetals from Group 16 are likely to form a-
A) triple and ionic bond.
B) double and ionic bond.
C) triple and covalent bond.
D) double and covalent bond.**
Use your reference copy of the Periodic Table to answer questions 4 and 5.
4. How can you describe the location of magnesium (Mg, atomic number 12) on the periodic table?
A) nonmetal
B) metalloid
C) Group 2, Period 3**
D) Group 3, Period 2
5. How many valence electrons does magnesium (Mg) have?
A) 12
B) six
C) three
D) two**
6. Which reaction is exothermic?
A) cellular respiration**
B) photosynthesis
C) baking soda + vinegar
D) melting ice
7. You are creating a carbon cycle poster. What could you include in the poster to demonstrate the cycling of carbon?
A) a rock falling
B) shells fossilizing
C) an eagle breathing**
D) the sun shining
8. Which chemical equation is balanced?
A) H20 H2 + 2O2
B) 2H20 2H2 + O2**
C) 2H2O H2 + 2O2
D) H20 2H2 + 2O2
11. When two hydrogen atoms bond with one oxygen atom to form water, what happens to the electrons?
A) Each hydrogen atom donates its electron to the oxygen atom
B) The oxygen atom donates an electron to each hydrogen atom
C) A pair of electrons is shared at each of the hydrogen-oxygen bonds**
D) No electrons shared or donated
12. Why is frying an egg an example of a chemical change?
A) atoms are lost during the reaction as bonds are broken
B) atoms are gained during the reaction as new bonds form
C) the products have dierent properties than the reactants**
D) the properties of the reactants are seen in the products
13. How did the discovery of the electron change the atomic model?
A) It disproved the earlier idea of an indivisible atom. **
B) It confirmed that atoms are very tiny.
C) It exposed fraudulent experiments conducted by unqualified scientists.
D) It proved that atoms are easier to see than once believed.
14. A student analyzed two diagrams of a nitrogen atom. Both diagrams showed seven protons in the nucleus, but the number of neutrons diered.
What are the two nitrogen atoms?
A) electrons
B) isotopes**
C) covalent bonds
D) ionic bonds
15. What is an arrangement of all elements showing the repeating pattern of their properties?
A) atomic model
B) electron dot diagram
C) periodic table**
D) chemical formula
I AGREE with all of your answers.
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1. To determine which of the following statements is true about photosynthesis, we need to understand what photosynthesis is. Photosynthesis is the process by which plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose (a type of sugar) and oxygen.
To determine if photosynthesis is an exothermic or endothermic reaction, we need to understand the definitions of these terms. An exothermic reaction releases energy into the surroundings, usually in the form of heat. An endothermic reaction absorbs energy from the surroundings.
Since photosynthesis uses sunlight energy to convert carbon dioxide and water into glucose and oxygen, it absorbs energy from the surroundings, making it an endothermic reaction. Therefore, the correct answer is B) It is an endothermic reaction.
2. Atomic theory is a scientific theory that describes the nature of atoms and how they combine to form compounds. It was developed by several scientists over many years and has been refined with new information and discoveries.
To determine whether atomic theory is subject to change if new information is discovered, we need to understand the nature of scientific theories. Scientific theories are evidence-based explanations that are subject to change or revision when new evidence is discovered.
Therefore, the correct answer is A) subject to change if new information is discovered.
3. To determine which two nonmetals from Group 16 are likely to form a double or covalent bond, we need to locate Group 16 on the periodic table. Group 16 is also known as the oxygen family and contains elements such as oxygen (O), sulfur (S), selenium (Se), and tellurium (Te).
Since the question asks about two nonmetals, we can eliminate selenium and tellurium because they are metalloids. Metalloids have both metallic and nonmetallic properties. Oxygen and sulfur are both nonmetals.
When two nonmetals form a bond, they typically form a covalent bond, where they share electrons. Therefore, the correct answer is D) double and covalent bond.
4. To describe the location of magnesium on the periodic table, we need to know its atomic number, which is 12. Looking at the periodic table, we can see that magnesium (Mg) is located in Group 2 and Period 3.
Therefore, the correct answer is C) Group 2, Period 3.
5. To determine the number of valence electrons magnesium has, we need to look at its position on the periodic table. Magnesium is located in Group 2, so it has 2 valence electrons.
Therefore, the correct answer is D) two.
6. To determine which reaction is exothermic, we need to understand the definition of exothermic. As mentioned earlier, an exothermic reaction releases energy into the surroundings, usually in the form of heat.
Out of the given options, cellular respiration is known to release energy during the process of breaking down glucose molecules to produce ATP (energy). Therefore, the correct answer is A) cellular respiration.
7. To demonstrate the cycling of carbon in a carbon cycle poster, we need to understand how carbon moves through various processes. Carbon cycles through the environment through processes like photosynthesis (plants absorbing carbon dioxide), respiration (organisms releasing carbon dioxide), decomposition (decay of organic matter releasing carbon dioxide), and combustion (burning of fossil fuels releasing carbon dioxide).
Out of the given options, an eagle breathing is an example of respiration, which releases carbon dioxide. Therefore, the correct answer is C) an eagle breathing.
8. To determine which chemical equation is balanced, we need to understand the concept of a balanced chemical equation. In a balanced chemical equation, the number of atoms of each element is the same on both sides of the equation.
Looking at the given options, we can see that option B) 2H2O 2H2 + O2 has an equal number of hydrogen and oxygen atoms on both sides of the equation.
Therefore, the correct answer is B) 2H2O 2H2 + O2.
11. When two hydrogen atoms bond with one oxygen atom to form water, they form covalent bonds. In a covalent bond, electrons are shared between atoms.
Therefore, the correct answer is C) A pair of electrons is shared at each of the hydrogen-oxygen bonds.
12. Frying an egg is an example of a chemical change because the properties of the reactants (egg white and egg yolk) change to form the products (cooked egg). During frying, the bonds in the proteins of the egg denature and form new bonds.
Therefore, the correct answer is C) the products have different properties than the reactants.
13. The discovery of the electron changed the atomic model by disproving the earlier idea of an indivisible atom. Before the discovery of the electron, the atomic model proposed that atoms were indivisible and that they did not contain subatomic particles. The discovery of the electron showed that atoms contain negatively charged particles that orbit the positively charged nucleus.
Therefore, the correct answer is A) It disproved the earlier idea of an indivisible atom.
14. The two nitrogen atoms described in the question are isotopes. Isotopes are atoms of the same element that have different numbers of neutrons. The number of protons remains the same, giving the element its identity.
Therefore, the correct answer is B) isotopes.
15. An arrangement of all elements showing the repeating pattern of their properties is called the periodic table. The periodic table organizes the elements based on their atomic number (number of protons) and their properties.
Therefore, the correct answer is C) periodic table.