Destiny is looking around her house, classifying changes she notices as physical changes or chemical changes. Which of the following is a chemical change? A. Destiny's father burns an English muffin.
B. Destiny's mother chops celery and onion into small pieces.
C. Destiny mixes chocolate syrup into a glass of milk.
D. Destiny's sister melts butter in the microwave.

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? a. the balloons both rise. the cold balloon is larger than the warm balloon. b. the balloons rise at the same rate. both balloons are the same size. c. the warm balloon expands and rises. the cold balloon shrinks and sinks. d. the cold balloon expands and rises. the warm balloon shrinks and sinks.

What was bohr’s contribution to the planetary model

What is the percentage of hydrogen in c2h4