Question

1. which would be the best tool to separate a mixture of sand and water?

filter magnet fire electricity

1. a water molecule is composed of 2 hydrogen atoms and one oxygen atom. which of

the following terms below does not best describe a water molecule?
compound element solvent pure substance

1. mixtures are only combined chemically, not physically.

true false

1. the smallest unit of an element that maintains the properties of that element is a(n)

molecule mixture atom compound

1. jenny is completing the table shown below.

what are the best headings for columns a and columns b?
column a: atoms column b: mixtures column a: elements column b: compounds
column a: molecules column b: atoms column a: atoms column b: elements

Explanation:

1.

Sand is insoluble in water. A filter can separate the solid sand from the liquid water. A magnet is for separating magnetic substances, fire and electricity are not used for this separation.

2.

A water molecule (\(H_2O\)) is a compound (made of different elements - \(H\) and \(O\)), a pure substance (has a fixed composition), and can act as a solvent. An element is a pure substance made of only one type of atom. Since water has two types of atoms (\(H\) and \(O\)), it is not an element.

3.

Mixtures can be combined physically (e.g., sand and water) or chemically. So the statement "Mixtures are only combined chemically, not physically" is false.

4.

An atom is the smallest unit of an element that maintains its properties. A molecule is made of atoms (e.g., \(O_2\)), a mixture is a combination of substances, and a compound is made of different elements.

5.

\(Na\) (sodium), \(Ca\) (calcium), \(Fe\) (iron), \(Pb\) (lead) are elements. \(NaCl\) (sodium chloride), \(CaCl_2\) (calcium chloride), \(Fe_2O_3\) (iron(III) oxide), \(PbN_6\) (lead hexanitride) are compounds (made of two or more elements chemically combined).

Answer:

1. filter
2. element
3. False
4. atom
5. Column A: Elements Column B: Compounds