Living organisms are largely made of carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur, which are all different types of __________.
a) electrons b) elements c) molecules d)cells
B) elements
100
The chemical reaction equation below shows that ___________ was applied.
CaCO3 --> CaO + CO2
a) Farady's Law
b) Avogradro's Law
c) conservation of matter
d) conservation of energy
Conservation of matter -- same kinds and numbers of atoms before and after the reaction.
100
How many products are produced by this reaction?
CH4 + 2O2 --> CO2 + 2H2O
2 products (CO2 and 2H2O).
100
A solution with a pH less than 6 is considered
a) acidic.
b) basic.
c) neutral.
d) ionic.
a) acidic
200
Which of the following represents a compound? Explain why.
A) H2
B) O2
C) O
D) H2O
D, H2O. A compound is 2 or more DIFFERENT elements bonded together.
200
If proteins, carbohydrates, and lipids (fats and oils) have a central role in the chemistry of living organisms, which element would they all have in common?
A. iron B. argon C. carbon D. calcium
C. carbon -- it's found in all living things!
200
An 8th grade student wrote a chemical reaction equation on the chalkboard that had two atoms of an element on one side of the arrow, but only one atom on the other side. Which statement about the equation is true?
A) This equation would violate the law of conservation of energy.
B) This equation would violate the law of conservation of matter.
C) This equation would violate the law of conservation of momentum.
D) This equation would violate the law of conservation of electric charge.
B) This equation would violate the law of conservation of matter. -- There should be the same number of atoms on the left and right side of the arrow.
200
Which statement correctly describes chemical reactants?
A) Substances formed during a chemical change.
B) Substances present before a chemical change happens.
C) The symbol that separates the substances present before and after the reaction.
D) Substances written on the right side of a chemical equation.
B) Substances present before a chemical change happens.
Reactants are the "ingredients" of a chemical reaction.
200
A group of students investigating the pH of saltwater in a fish tank use a pH indicator to determine that the pH value is 8.2. This means that the saltwater is __________.
a)a weak acid
b)a weak base
c)a strong base
d) neutral
b)a weak base
The closer the pH is to 7, the weaker it will be.
300
True or false. (If false, explain) When 2 different elements react chemically, the products of the reaction will most likely have the same chemical and physical properties than the original elements.
False. A reaction will always form products with DIFFERENT properties as the original elements or reactants.
300
Which of the following choices would most likely contain the element carbon?
A. metal rod
B. table salt
C. water lily
D. distilled water
C. water lily
It is a plant, a living thing. Carbon is found in ALL living things.
300
100 grams of iron nails are exposed to oxygen in the air and are allowed to rust. When the nails are weighed they have a mass of 150 grams. In order to obey the law of conservation of matter, which choice is the amount of oxygen that must have reacted with the iron to form iron oxide (rust)? Explain.
a) 50 grams b) 100 grams c)150 grams d) 250 grams
a) 50 grams.
The mass of the reactants (100g+50g) must equal the mass of the products (150g).
300
Hydrogen chloride is formed when chlorine (Cl2) gas and hydrogen (H2) gas combine. Which of the following would be considered the product of this reaction?
a) chlorine
b) hydrogen
c) hydrogen chloride
d) hydrogen and chlorine
c) hydrogen chloride -- The problem also tells you that "hydrogen chloride is formed when..."
300
Most human enzymes (a molecule in the bloodstream of living things) work only in environments with a neutral pH. When measuring the pH of blood, an investigator would predict a pH value of close to _________.
a)2 b) 5 c) 7 d)13
c) 7 -- neutral pH
400
When a metal element chemically reacts with a nonmetal element, a(n) _________________ bond is formed between them.
An IONIC BOND is formed between a metal and nonmetal element.
400
Carbon dating is a method that is commonly used to find the age of plant and animal fossils, which statement is the reason why this dating method is possible?
A. Carbon plays a central role in the chemistry of all living organisms.
B. Carbon plays no central role in the chemistry of all living organisms.
C. Carbon plays a central role in the chemistry of some living organisms.
D. Carbon is a part of everything both living and non–living.
A. Carbon plays a central role in the chemistry of all living organisms.
400
H2 + O2 → 2H2O
Which statement correctly supports the argument that the illustrated chemical equation shown violates the law of conservation of matter?
A) There are more oxygen atoms on the left side of the arrow then on the right side.
B) There are more hydrogen atoms on the left side of the arrow then on the right side.
C) There are more oxygen atoms on the right side of the arrow then on the left side.
D) There are more hydrogen atoms on the right side of the arrow then on the left side.
D) There are more hydrogen atoms on the right side of the arrow then on the left side.
400
Atoms and molecules combined at the start of a chemical reaction are known as _________
Reactants
400
A research team in a major metropolitan area measures the pH of rainwater to be 6.1. This means that the rainwater is __________.
a) a strong acid
b) slightly basic
c) neutral
d) slightly acidic
d) slightly acidic -- The closer to 7 the pH is, the weaker it will be.
500
The bonds between the elements in H2O are __________ (ionic or covalent). Explain.
COVALENT bonds are formed between nonmetal elements like hydrogen and oxygen.
500
What are the 4 major types of molecules (also known as macromolecules or biomolecules) found in ALL living things?