PSSA Review 8th grade Science

Front

Which of these is an example of a compound?

• Two fluorine atoms bonded together
• A piece of solid gold made of millions of gold atoms
• An atom of nitrogen bonded to three atoms of hydrogen
• A drop of liquid mercury made of millions of mercury atoms

Back

An atom of nitrogen bonded to three atoms of hydrogen

Front

A scientist combines three elements and observes the results. She concluded that the elements formed a compound when they combined. Which observation best supports this conclusion?

Back

The combination of the three elements had some properties that none of the elements had.

Front

What are the reactants in the chemical reaction that forms rust?

Back

Water, iron and oxygen

Front

Which of the following is a compound? Solid Gold (Au), Nitrogen gas (N2), Liquid Water (H2O), Hydrogen Gas (H2)

Back

Liquid Water (H2O)

Front

Which of the following is an example of chemical change?

• A chunk of metal being hammered flat
• a piece of chalk being crushed into powder
• a solid rock melting into magma
• an iron bridge turning brownish over the years

Back

an iron bridge turning brownish over the years

Front

Chemical reaction: K₂S decomposes into potassium and sulfide.

Back

K₂S ----> K + S

Front

What never changes during a chemical change? Options: arrangement of atoms, number of molecules, total number of atoms, color of the reactants.

Back

total number of atoms

Front

Which of the two combinations most likely produced a mixture? Options: 1 and 2, 1 and 3, 2 and 3, 3 and 4

Back

3 and 4

Front

What did combination 4 produce?

Back

A mixture that was physically combined

Front

Why did the black metal in combination 3 sink to the bottom of the liquid?

Back

It had a density greater than the liquid it was placed in.