t2

Question 1

physical change are substances

Answer 1

substance changes in form but not in chemical composition

Question 2

chemical change causes

Answer 2

causes one or more new substances to be formed

Question 3

what is produced or absorbed in chemical change

Answer 3

heat

Question 4

examples of chemical change

Answer 4

burning of milk
digestion of food
rusting of iron
photosynthesis
burning of wood/paper

Question 5

observes of chemical change

Answer 5

difficult/ impossible to recover

usually, heat is produced/ absorbed

starting material may be used up

change in color may occur

gas bubbles

may form in a liquid

a precipitate may form in a liquid 沉淀

Question 6

examples of physical change

Answer 6

hammer
dissolution of sugar in water
shattered glass
change of state (melting of ice/ boiling of water)

Question 7

chemists need to classify ________- of materials to understand them better

Answer 7

properties

Question 8

3 properties to be classified lol

Answer 8

color, density, combustibility

颜色、密度、可燃性

Question 9

how would you tell a balloon is filled with helium or hydrogen

Answer 9

expose to flame and test combustibility (ability to burn)

Question 10

combustibility is a chemical property since it

Answer 10

describes how a substance reacts with another substance when forming a new substance

Question 11

physical properties can be classified as .....
\_\_\_\_\_\_\_\_ can be measured numerically, usually with an apparatus
or \_\_\_\_\_\_ (can be described but not measured,

Answer 11

quantitative

qualitative