Химия

Examples are water (H₂O) and carbon dioxide (CO₂).

• elements
• mixtures
• compounds

Tags

NGSS.MS-PS1-1

A pure substance containing only one kind of atom.

• element
• mixture
• compound

Tags

NGSS.MS-PS1-1

What type of mixture is this?

• homogenous mixture
• chemical
• heterogeneous (mechanical) mixture 
• solid mix

Which of the following is NOT an example of suspension ?

• fog
• cream (from milk)
• muddy water
• apple  juice

3 examples of a physical change...?

• sawing of wood, crushing a can, & toasting a marshmaollow
• freezing water, bursting of a balloon, & rotting of an egg
• boiling of water, bursting of a balloon, & crumpling a piece of paper
• evaporation of gasoline, rusting a nail, & freezing of water

Which of the following is NOT a clue that a chemical change is taking place?

• rapid release of energy (heat, light, or sound)
• phase (solid-liquid-gas) change
• formation of bubbles
• formation of a precipitate from solution

Tags

NGSS.MS-PS1-2

Mr. Kim shows his students a mixture of plastic beads and metal beads. He then uses a magnet for demonstration. What is he MOST LIKELY demonstrating?

• making a solution
• separating a mixture
• creating a chemical change
• changing the state of matter

Mr. Kim lit a candle and described to his students that some of the wax is burning while some of the wax is melting. Student A states that these are both physical changes. Students B states that these are both chemical changes. Which statement BEST describes the students' conclusions?

• Student A is correct.
• Student B is correct.
• Both are incorrect, because burning wax is a chemical change and melting wax is a physical change.
• Both are incorrect, because burning wax is a physical change and melting wax is a chemical change.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

What does it mean to dilute a solution?

• lower the concentration of solute per solvent
• increase the concentration of solute per solvent
• no more solute can be dissolved in the solution
• a solution contains more of the solute than the saturated solution can hold

On the pH scale what number is the most acidic

• 13
• 0
• 1
• 4