Which of the follow is not a physical change? a. The boiling of room temperature water to produce steam.
b. The combustion of hydrogen gas and oxygen gas to produce liquid water.
c. The cutting of a block of sharp cheddar cheese to make smaller pieces for hors d'oeuvres for a social gathering
d. The slow melting of solid coconut oil on the stove.

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.

Select the correct answer from each drop-down menu.describe what happens to a carbon-11 atom when it undergoes positron emission.the decay of a carbon-11 atom _1_, and this causes it to emit _2_.options for 1: > changes a neutron into a proton> changes a proton into a neutron> is hit with a neutron> reconfigures its protons and neutronsoptions for 2: > a negatively charged electron-sized particle> a positively charged election-sized particle> two atoms and several neutrons> two neutrons and two protons

In the following table, all the columns for the element calcium are filled out correctly. element electron structure of atom electron structure of ion net ionic charge calcium 1s22s22p63s23p64s2 1s32s22p63s23p64s1 +1 true false