Which of the following is a clue of a chemical change?

a. balls of wax form when melted wax is poured into ice water

b. iron changes color when heated

c. gas bubbles form in boiling water

d. a gas forms when vinegar and baking soda are mixed?

Member of group 17 on the periodic table

Mary and Chuck each pull at opposite ends of a rope. Chuck is stronger. Who will move backwards? The rope will move but Mary and Chuck won't Both Mary and Chuck will move forward Chuck will move backwards Mary will move backwards

A combustion analysis of a 0.503 g sample of an unknown hydrocarbon yields 1.53 g CO 2 2 and 0.756 g H 2 2 O.

What is 823,549 rounded to three significant figures?

Which of the following phrases describes core electrons? A. Electrons that are involved in chemical reactions B. Electrons that determine an atoms properties C. Electrons that are farthest from the nucleus D.

Two pure elements react to form a compound. One element is an alkali metal, X, and the other element is a halogen, Z. Which of the following is the most valid scientific claim that can be made about the compound? a. It has the formula XZ2 b.

Are protons positive and neutrons neutral

Why might it be useful to determine the elements that a planet or moon is made up of?

Which of these is an example of a solution A Sand stirred in water B Sugar stirred in tea C A glass of water with ice in it D Oil and vinegar in a salad dressing jar

What are properties of colloid