Water is a compound because it
1. a can be broken down into hydrogen and oxygen
2. has a fixed composition
3. is made of water atoms joined together
4. both 1 and 2
1. A substance made up of only one atom is an element
2. Milk is a colloid
3. A mixture that appears to contain only one substance is a homogeneous mixture
4. Water is a compound because it always has 2 hydrogen atoms for each oxygen atom
5. A jar of mixed nuts
4. both 1 and 2
The correct answers for the Unit 2 Lesson 1 quick check are:
1)C
2)C
3)A
4)D
5)C
The correct answer is option 4: both 1 and 2.
Water is a compound because it satisfies both the conditions mentioned in options 1 and 2.
1. Water can be broken down into hydrogen and oxygen: This is known as the process of decomposition (or electrolysis). By passing an electric current through water, it can be separated into its constituent elements, hydrogen and oxygen. This demonstrates that water is made up of hydrogen and oxygen atoms.
2. Water has a fixed composition: Water is always composed of two hydrogen atoms and one oxygen atom, represented by the chemical formula H2O. Regardless of its source or location, water will always have this fixed composition. This is a characteristic feature of compounds, where the constituents combine in fixed proportions.
Therefore, water meets both conditions: it can be broken down into hydrogen and oxygen, and it has a fixed composition of two hydrogen atoms and one oxygen atom. Hence, the correct answer is option 4: both 1 and 2.