7th Grade Science CASE-most missed Questions

Which occurs in a chemical reaction due to the Law of Conservation of Mass?

• The reaction causes the destruction of atoms and a decrease in total mass.

• The reaction causes the creation of atoms and an increase in total mass.

• The mass of atoms do not change even if the atoms form new arrangements.

• The mass of atoms do not change, and the atoms cannot form new arrangements.

Tags

NGSS.MS-PS1-5

How can the water and ether be separated so that only one remains in the beaker?

• by heating the mixture to 100°C

• by heating the mixture to 35C

• by cooling the mixture to 0°C

• by cooling the mixture to -116°C

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

An atom has 21 protons, 24 neutrons, and 18 electrons. Which change will cause the atom to have more negatively charged particles than positively charged particles

• losing 2 protons

• losing 4 neutrons

• gaining 3 electrons

• gaining 4 electrons

Which property would be least useful in identifying an unknown substance, and why?

• Reactivity; this is a chemical property that changes depending on the size of the substance.

• Melting point; different pure substances can have the same melting point.

• Color; this is a physical property and cannot be used to identify substances.

• Mass; physical and chemical properties stay the same with a change in mass

Why does the boiling point decrease at higher altitudes?

• As pressure decreases, the intermolecular attractions between water molecules decrease.

• As pressure decreases, the intermolecular attractions between water molecules increase.

• As pressure increases, the intermolecular attractions between water molecules decrease.

• As pressure increases, the intermolecular attractions between water molecules increase.

Where are the electrons, protons, and neutrons located in an atom?

• Protons and electrons are inside the nucleus, and neutrons are outside the nucleus.

• Protons and neutrons are inside the nucleus, and electrons are outside the nucleus.

• Electrons are inside the nucleus, and protons and neutrons are outside the nucleus.

• Protons are inside the nucleus, and electrons and neutrons are outside the nucleus.

Which 2 elements have properties of both metals and non-metals?

• beryllium (Be)

• iron (Fe)

• silicon (Si)

• tellurium (Te)

• tungsten (W)

When methane gas (CH4) is mixed with water vapor (H2O) at very high temperatures, hydrogen gas (H2) and carbon dioxide (CO2) are formed. A student claims that hydrogen gas is a noble gas because it is a stable molecule. Which argument proves the student’s claim is incorrect?

• Noble gases are stable at room temperature, and hydrogen gas forms at high temperature

• Noble gases are monoatomic elements, and hydrogen gas is a diatomic element.

• Noble gases form molecular compounds, and hydrogen gas does not form molecular compounds.

• Noble gases have the same number of electrons, and hydrogen gas has fewer electrons.

Tags

NGSS.HS-PS1-1

Which describes the subatomic particles of a neutral helium atom?

• four protons, four neutrons, and four electrons

• two protons, four neutrons, and two electrons

• four protons, two neutrons, and two electrons

• two protons, two neutrons, and two electrons

Tags

NGSS.MS-PS1-1

How many grams of molecule Z are formed from the reaction?

• 35 g

• 25 g

• 10 g

• 5 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5