Why are sodium (Na) and potassium (K) in the same group on the periodic table? (1 point)
• They are both hard and brittle.
• They have similar reactivity.
O They have similar atomic weights.
• They are both colorless.
• They have similar reactivity.
A student cuts some fabric into two pieces. Is this change physical or chemical? (1 point)
• It is a physical change because there is no reaction.
O It is a chemical change because there is no phase change.
• It is a chemical change because the size changes.
• It is a physical change because the process is reversible.
• It is a physical change because the process is reversible.
How are chemical changes different from physical changes? (1 point)
• They are reversible.
• They involve heat.
• They form new substances.
O They include shifts in the phase of matter.
• They form new substances.
How does a balanced chemical equation demonstrate the Law of Conservation of Mass? (1 point)
• it shows that only physical changes follow the Law of Conservation of Mass
• it shows that all compounds remain bonded after the reaction
• it shows that no atoms have been gained or lost during the reaction
• it shows that the properties of the elements stay the same after the reaction
• it shows that no atoms have been gained or lost during the reaction
Which procedure could be used to demonstrate that matter is conserved during a physical change? (1 point)
• Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
• Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
• Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
• Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
• Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
One molecule of bromine (Br) and two molecules of potassium chloride (KCI) combine in a reaction. How many atoms are in the products? (1 point)
• three
• two
O six
• four