Which question cannot be explained by chemistry? a. how does yeast make bread dough rise? b. why does sugar dissolve faster in hot water? c. how does a convection oven cook food? d. why do peeled apples turn brown in air?

Which is true of the reactants in this displacement reaction? fe + 2hcl fecl2 + h2 a. the reactants are located to the left of the arrow in the chemical equation. b. the reactants contain 1 iron atom, 2 hydrogen atoms, and 1 chlorine atom. c. the reactants are the atoms, molecules, or compounds formed in the reaction. d. the reactants have the same physical and chemical properties as the products.

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

What are the two major rules associated with polarity